Elemental (PvE)/Elemental (PvP) - This particular dual spec would make use of specific elemental shaman burst damage abilities and picking up Nature's Swiftness from resto in order to cast a chain lightning instantly. With the changes to Elemental Mastery it's not as attractive as it was (you can't guarantee an opening crit and the chance of using Flame Shock/Lava Burst in PvP isn't as good, and Lava Burst won't be affected by Nature's Swiftness) but it's still viable.
Elemental (PvE)/Restoration (PvE) - While the gear isn't exactly equivalent (restoration still prefers MP5 and pushes crit more than elemental does now, since elemental can make use of Flame Shock/Lava Burst to guarantee a crit whenever it needs one for Clearcasting and has access to Unrelenting Storm, a talent most resto shamans won't have as it is 21 points in elemental) there's still enough overlap to make this particular spec combination probably the most compelling. Frankly, I often see elemental shamans asked to off-heal on hard fights or even just in hard parts of fights (our elemental spams a lot of chain heal during Maly's vortex) so the real issue here is in carrying a couple of pieces with high MP5 to make the switch, and even then you might be okay if you have enough crit to proc the restoration abilities like Ancestral Awakening.
Restoration (PvP)/Restoration (PvE) - You know this is going to happen. PvP resto is about healing, yes, but you need as much survivability as you can get in the burstorama that is current PvP. Are you going to take Healing Grace in your PvE resto build? (I do at times, but people keep telling me that the threat reduction isn't necessary and so ar they seem to be correct) But having the dispel resistance in PvP is almost mandatory. (It would be mandatory if it wasn't a mere 30%)
Enhancement (PvE)/Elemental (PvE) - Why do I think this spec is likely, when it's just two DPS specs, and both aimed at the same content? Because Blizzard is notorious for designinging some fights with so much AoE damage, so many places on the floor that the melee has to move out of, and so on that there almost has to be an attraction to a raid leader in a fight where he can turn to some of his DPS and say "Hey, can you respec so that we can reduce the healing load some here" without immediately extending the fight by five or six minutes.
I also expect this particular dual spec to exist because enhancement is the best spec for grinding a bunch of dailies or farming. Elemental has plenty of DPS, but Maelstrom Weapon means that a shaman can instant cast a heal which means much less downtime between mobs. (Of course, once your elemental shaman has sufficient gear this is no longer an issue.) Also, some time syou feel like smashing faces, and sometimes you feel like burning them off from ways away. My biggest sadness is that I won't be able to be enhancement/elemental/restoration because frankly I'm at the point now where all three specs appeal to me.
Enhancement (PvE)/Restoration (PvE) - I actually don't think this will be as popular as elemental/resto, because enhancement gear still doesn't really have the spellpower or MP5 or anything resto wants, meaning there will be more 'does he have even remotely suitable gear' discussions. However, it's hard to imagine raid leaders disliking having the flexibility of having DPS become healing or vice versa depending on the needs of the particular fight, especially as we start trying our luck in Ulduar. After all, any spec of shaman can cast Bloodlust/Heroism.
Enhancement (PvP)/ Enhancement (PvE) - Stop laughing. Okay, we know shamans still suffer in PvP from their low health compared to other melee and an inability to really escape snares. The few talents in enhancement that help with PvP (Anticipation, Toughness) are generally the ones you don't take for PvE.
Restoration (PvP)/ Enhancement or Elemental (PvE) - A PvP resto spec is still adequate for switching to offheal a raid encounter that needs just a little more healing oomph, and also generally would have the benefit of more survivability talents in the case of a raid encounter with splash damage or ridiculous "aah, the floor is suddenly evil and I can't stand here" moments. God, I hate that mechanic. In real life I rarely have to worry about the floor trying to kill me. Rarely. Sometimes the trap door springs unexpectedly. Another possibility would be Restoration (PvP)/ Enhancement or Elemental (PvP) of course. I don't know how well the idea of having two PvP specs is going to work (it depends on how well we can actually change specs - will the Libram allows us to before an Arena match?) but it's certainly a possibility we shouldn't ignore.
That's this week's Totem Talk. What dual specs am I missing?