"It's possible health in general is low for shamans" comes the response in a thread about Shamans in PvP. The dev's, we are told, are looking at elemental and enhancement shamans in 3.1, specifically in the area of their survivability in PvP. Is the culprit too much burst? Are shamans simply too squishy? We're not given any real specifics, but the fact that health is specifically mentioned as possibly the culprit is very interesting. To be honest, I'm not sure how you'd fix it. Putting more stam on Enhamcement mail would mean that Hunters would also go up in health, which to be honest I don't have a clue about. It seems more likely to me that shamans will simply get more benefit from the stamina already on their gear.
At any rate, PvP shamans, something is coming for 3.1, although we have no idea what as yet.