Well, if you're planning ahead for Wrath, there are a couple things to look at.
If you're going PvE, humans are potentially better for the spirit bonus and the "feign death." And of course, Diplomacy.
Gnomes, on the other hand, get passive arcane resistance (I think it's being modified to reduced damage taken) and an intellect bonus (extra mana/crit).
If you're going PvP, it's becoming a bit more indecisive, but I think gnomes still win out.
Extra mana/crit + Escape Artist + Arcane damage reduction vs. extra spirit (slightly better life taps) + trinket + passive 1 level stealth detection (Perception is actually far better in its current form, but what can you do?).
Edited, Sep 27th 2008 3:17pm by wingsofscion