A lot of people saying here that they don't think Shaman tanking is possible... I personally have tanked heroics before in tank off-spec gear and PvP gear. It is possible and if you check this guy who has been tanking for some time now you will be truly amazed as I first was:
http://www.wowarmory.com/character-s...mi&gn=Masquers
I believe he gets hunters MD'ing him and tricks throughout fights. Also to people saying there are not enough defensive abilities for a Shaman to tank is not valid (Stoneclaw totem, trinkets, wolves, shamanastic rage etc.)