In theory, the phone should be able to run 2.2. We just don't have any idea how quickly Samsung will get it packaged up as a firmware for us.
For me honestly, by the time 2.2 makes it on to the Moment, I suspect that I'll have moved to another handset.
I like the moment a lot (I really haven't had a the problems that others here have had), but new phones are coming out so fast, I have a feeling I'll jump to a newer device sometime late fall or early winter (November will be a year that I've had the Moment).
I'm not sure what all the differences will be. Supposedly there are a bunch of performance tweaks in 2.2 that should significantly improve speed.
-SF