I don't want to invoke BTPNTC again, but it's a common perception that one of the goals in class balance in Wrath has been to bring the damage various DPS specs more in line with each other. This, in turn, has raised questions like "if a feral druid does as much damage as a rogue, what's the point of the rogue?" This question is arguable, but fortunately, that lovable crustacean Ghostcrawler has laid bare the developers' goal for how the classes should be positioned relatively in terms of DPS.
Here it is:
- Hunters, mages, rogues, and warlocks.
- Everyone else.
It's important to note that the gap between 1 and 2 is meant to be quite small, and that it will probably be swallowed up by gear, player skill, and the particulars of individual encounters in most cases. As GC puts it, "If you know your class cold, I mean really know it, then there is no reason you can't be topping meters."
I think this is a good design goal. The pure classes have a slight edge, but skilled players of any class should do well. Of course, we're not quite there yet, class balance being a perennially moving target, but they're working on it.