I expect this update will have the obvious bug fixes. Although, I am quite happy with 2.0, there is no question that its a bit rough around the edges and probably not complete.
The other thing I kind of expect is possibly more minor or small features that were in the 2.0 code, but too unstable for launch. I'm sure there was a point of no return where they had to simply cut out anything that was a deal breaker in order to make the deadlines.
Either way, just like anything Apple does it will get better with time. Look how long Leopard has been out and we are already at its 5th release. I think its pretty obvious Apple had some enormous hurdles with 2.0 and the sdk etc. Hopefully now they can get all the 2.x code stable and refined.... then start working on the backlog of feature requests.