I just started 3 shamans two weeks ago and I believe they aoe just as well, if not better than mages in some cases.
I drop stone talon totems and then cast fire nova follow by magna. I can usually take down a large pack without healing too much.

I leveled my orignal shaman to 70 using aoe tactics. The exp was fantastic in some areas, but questing is much better towards the mid 40's