I have been wondering about this myself. My current plan is to take 5 shaman into northrend and see what they can do. I am tempted to add a lock to the group so they can all benefit from the curse that would be placed on the boss. Shaman are pretty much trash clearing machines right now. Grounding totems makes ranged easy and thunderstorm makes melee easy. I think only time will tell on what is the best group.

Right now it looks like shaman at level 80 might not be in the same ballpark dps wise as some of the other casters. I am sure that if this is the case then we should see a buff to elemental shaman at some point. So the way I figure it is you struggle leaning new content but will probably eventually get it down. Then if you get a buff everything becomes that much easier