At this point, the rigid body dynamics, and some work on the existing simulations (particles, cloth) is still on the schedule for a subsequent versions. As Ed is suggesting, feedback is very important to us, specially if you give us concrete example of production scenarios and problems that you would like to see solved, rather than just a list of features. This helps us validate and adjust our development process.
This being said, I think that we have managed to make XSI v2.0 a strong contender to Maya v4.0, and the feedback we keep getting from our users is not so much that we match or win the feature list war, but that we make the production process easier and faster.
Right now, in the post-production area in New-York, the XSI companies are grabbing the lion share of the jobs because they can on average turnaround the same or better quality productions in a third of the time.