New team, new server, all trolls, what classes?

[Solon]

While I hadn't considered druid, it is a good idea. The problem I have is this is to be a troll team and I may not get Cataclysm, and I doubt I will wait to make the team until Cat comes out. At this point the common answer seems to be
Tank: Warrior
Healer: Priest
DPS1: Mage
DPS2: Hunter
DPS3: Shaman

What does the hunter bring to the team? My first 60 was a hunter, and I have a PvP team of hunters, but I don't see what they would bring over another mage or shaman.

EDIT: Also, what would you change if my goals were to change to 5 man PvP, such as battle grounds and Wintergrasp.