Oh so elemental...

Here is the raiding elemental spec that I'm running with right now. There's not really much that's up for change in it, the points in Eye of the Storm could be moved for something like the decreased shock cooldown, but there's not much else.

The play style is very simple too. Recast flame shock to keep it up all the time, try to refresh it right after it falls off, but if that would mean delaying a Lava Burst, recast it earlier. If there are multiple enemies and you have the mana, cast Chain Lightning when it's off cooldown, otherwise, spam Lightning Bolt.

Gear

There's only 1 type of mail caster gear out there, and you share it with Resto Shaman. This does mean that you won't find any mail caster drops with hit rating on them. So you'll have to get your hit rating from tier pieces, gems, enchants, and non-armor equipment. Crit is an important stat for Elemental Shaman, but only up to a certain point, I've found 33% to be a decent amount to have while raiding (buffs included).

Other than satisfying that and your hit cap, you're going to want haste and raw spellpower. Elemental Shaman scale very well with spellpower because our crit multiplier for spells is 2.5. Haste won't have very tangible benefits for a while, because your spell casting is based around casting Lava Burst whenever it is ready, so you'll find yourself waiting and not casting spells while the last .5 seconds or so tick off of Lava Burst. But, if you stack enough haste, you'll find that you can cast 5 Lightning Bolts in between Lava Burst, and that's when it will really start to pay off.

As far as mana regen goes, Elemental Shamans have it pretty easy because we get 12% (approximately 1/8th) of our Intellect as MP5. When you're undergeared, make sure and have enough MP5 to last a battle, but as you're gearing up, you'll be replacing MP5 with Intellect, so you don't have to worry about MP5, and let those itemization point go towards MORE SPELLPOWER!

I honestly don't know what else to say. I had so much to say about Enhancement, this feels like so little. Oh...wait, AHA!

More on playing

It's definitely worth noting that stunned creatures will not be moved by Thunderstorm. This is a good thing. If you decide to take Improved Fire Nova Totem, you can get 1 big burst of damage, stun them, Thunderstorm, drop Magma Totem, and then step back to do Chain Lightnings. I chose to Glyph away the knockback from Thunderstorm for more mana. So I run in and drop Magma Totem, Thunderstorm, and run back out.

Don't forget Elemental Mastery, it's one of the only cooldown abilities that increases DPS and saves you Mana. Note that the increased crit chance will give you more clearcasting procs.

Ok, I'm pretty sure that this is all that I have to say.

3.0.8 PVE Enhnacement

Here is my raiding Enhancement spec of choice.

Basic Play

It's played by using Stormstrike, Lava Lash, and Earth Shock when the cooldowns are up and Lightning Bolt whenever Maelstrom Weapon is stacked to 5. In AOE situations use Chain Lightning but watch your mana, because it drinks it up.

Weapons

Should you use a slow Main Hand weapon w/ Windfury and a fast offhand weapon with Flametongue, or use 2 slow weapons both with Windfury? I've read that both playstyle do comparable damage (somewhere on Elitist Jerks). So you should use the best slow weapon available for your main hand and the best offhand you can get your hands on, fast or slow (not medium speed), and enchant it appropriately.

Gear

You should be wearing "hunter" mail that has AGI, INT, AP, HIT, CRIT, HASTE, and MP5. Armor Pen isn't very useful because of all of the spell damage Enhancement Shamans do. Don't stack spellpower because you will get spellpower from your attack power. Haste is also less useful for enhancement shamans because it will only help with your Autoattack and Maelstrom Weapon damage, because your other damage is limited by your cooldowns. In 3.1, Shamans (among others) will see increased benefit to their melee attack speed from haste, so this could change.

Hit Rating

Because Enhancement Shamans are a dual wield and spell caster class, hit rating is VERY important. The consensus is that you should get enough hit rating to negate the chance for your spells to miss, this will also make Stormstrike and Lava Lash never miss. At that point, your autoattacks will still miss, but it's believed that you will gain more by stacking other stats at that point. Spells normally have a 17% chance to miss against a level 83 (i.e. raid boss) target. Remember that Draenei provide a +1% chance to hit, and that Shadow Priests and Boomkins provide +3% chance to hit to the raid. So you might only need 16%, or 14%, or 13%.

Remember that your attack power formula is STR+AGI+INT, and that AP*.3 = Spellpower. These provide the core of your damage.

Having Mana Issues? Stack more Int, MP5, and Crit. MP5 will help the most. Int will help you last longer but won't do much more help in the long term. Crit will boost damage and efficiency through clearcasting. Remember an OOM Shaman is a lame shaman.

Advanced Play

About Maelstrom Weapon. You should use a 5 stack of Maelstrom before you use Stormstrike or Lava Lash, because SS and LL can get you more Maelstrom Weapon procs. If Maelstrom is at 5 stacks and you use SS or LL, you may get a MW proc that is wasted.

I would begin each boss fight by going crazy, wearing Lightning Shield and casting all of the spells that you can, to run your mana low, and then use Shamanistic Rage to fill it back up, then run yourself back down low (not OOM) and switch to Water Shield, and try to hover at a good value until Shamanistic Rage is back, so it will fill you back up. This, of course, varies from battle to battle. On Maexxna, I would make sure that I have full mana and the Wolves are off cooldown before she goes into a frenzy so that I can maximize my DPS during that particularly trying time.

It should also be noted that enhancement mana regen will be greatly aided in 3.1, since Improved Stormstrike is going to be rolled into normal Stormstrike, and Improved SS will give a 50%/100% chance to regen 20% of your base mana when you use Stormstrike. It's worth nothing that SS costs 8% of your base mana , Lava Lash is 4%, Earth Shock is 23%, and Lightning Bolt is 17% (all numbers before applicable cost reductions). There seems to be some consensus on Elitist Jerks that the regen provided by Improved Stormstrike isn't needed by raiding Enhancement Shamans. I say that the regen provided by it allows the shaman to stack fewer mana stats on their gear and focus more on damage stats.

As your gear improves you can swap points out of mana conservation talents to more damage talents if your mana regen can handle it.

That's all I have for now.

Totems of Note: UK, AN, and AK

Utgarde Keep

Like the Nexus, Utgarde Keep is pretty basic.  Use the same totems you always use.  Not even resistance totems will be that useful.  You should keep in mind that the runecasters will cast a dispelable magic shield, so watch out for that.  

Azjol-Nerub

This instance has a mechanic which comes up often, AOE poison.  Each of the bosses either has an AOE poison, or one of their adds has an AOE poison.  On Krik'thir the Gatewatcher, the group of adds on the left has an AOE poison, Hadronox casts an AOE poison, and the Venomancer on Anub'arak (Heroic only) cast an AOE poison.  I know what you're thinking, I should use Poison Cleansing Totem, and you're right.  The trick is that when you cast PCT, it immediately does a cleanse, so you can wait until the AOE poison happens and you can cleanse it immediately.  Bam.  Boom.  Done.

Ahn'kahet

I hate this instance,  I just figured that I would go ahead and say that now.

The first section of the instance features AOE poison like Azjol-Nerub, this comes from the Nerubians on the early trash pulls.    There is also a disease before the first boss (depending on which way you go) but it's not that bad.  Speaking of the first boss, he's a tricky little bugger, but you just use your normal totems.  Just remember to kill the guardians to drop the shield.

On the way to the second boss, you have to go up to the platforms to click on the orbs.  The only thing that could be useful on those pulls could be some Frost Resistance Totem, but that's not going to help much.

Second boss, Prince Taldaram.  For this one, Fire Resist is good, and you won't miss the lack of a water totem.  

The trash after Taldaram is pretty rough, pulls need to be careful.  If I remember correctly, there is a fear effect in Jedoga Shadowseeker's area, so keep that Tremor Totem down.  It's just a shame that it got nerfed to its intended effect.

If you go to the left, on Heroic, Amanitar is there.  Nothing special here for totems.  Jedoga doesn't have any special totem needs either.  But Herald Volazj is cool.  Twice during the fight, he will do Insanity on the group.  Causing your teammates to turn against you.  If you're DPS, your job is to kill the insanity clones, and then when yours are killed you go help one of your group members finish off theirs.  To do this, you're going to have to finish off the healer of the group first, using Earth Shock to cancel the heals, and Magma totem to keep the healer busy.  Fire Nova Totem is useful if you have the stun talented into it.  If you're the healer, your job is to survive until someone can help you, use Eartbind Totem to keep them off of you, and Earth Shock to keep them from hurting you, and keep yourself healed.

I'm out.

Totems of Note

Heroics, we do them, we love them, we hate them. But regardless of how you feel about totems, you know that even if they are annoying at times, they are powerful. So I'm going to be doing a series of posts of which totems are useful in particular dungeons. I'm going to be going dungeon by dungeon and explaining what totems are awesome in what situations.

The Nexus -
There's not really much here that's helpful. If you don't have a well-geared group. You may consider using fire and frost resist on Grand Magus Telestra and Frost Resist on Keristrasza. Anomalus, Ormorok, and the Horde or Alliance Commanders there's not much new.
As for the trash, there's nothing special here. The Nexus is a pretty basic instance which doesn't have alot of the tricky mechanics of a higher level instance.