Xobni is pretty cool. Email really is the killer app and Xobni adds a few nice features to it. Xobni search is very quick, and I like being able to see files that I have exchanged with different users and the conversation threading. Most of the rest of the app is just eye candy though. Really nice eye candy, but eye candy nonetheless. I see microsoft adding the useful features in a next release.
I guess the answer is, Xobni, sorry, nope not really.