Wikidot now says that shamans have a new spell. It is in the section that usually has confirmed abilities but we can't say for sure that it is not just a mob ability.
Here it is; Hex - Transforms the enemy into a random critter, reducing the target's movement speed by 75%. While moving, the hexed target cannot attack or cast spells. Only one target can be hexed at a time. Only works on Humanoids and Beasts.
Sorta seems like polymorph without a heal... looks like shaman are gonna be very desired in pve + imagine this in pvp.
Heres the link
WotLK Information Wiki: Shaman Abilities