Mages do better dps then shamens.
Int buff gives more max mana, and a little crit
Dampen magic for slaves, amplefy magic for tank (unless to meny casters)
And as well the focus magic spell from the arcane tree looks realy nice. (WoTLK talent)
and maby(these arnt totaly desided yet but they could be in the talent tree of mages) :
imp scorch: your scorch spell have a 100% chance to cause your target to be vulnerable to spell damage, increasing spell critical strike chance against that target by 2% and lasts 30 sec. stacks up to 5 times.
Thats how it looks by now on the test server.

Thats proberly the things for incombat benefits you get, but there will be a some stuff out of combat which is nice by having a mage:
water/food
portals

So yes, fuck the shamen..