So far I've been accepted to Northwestern and U of illinois (I think I'm the first to mention U of I). I heard from both on the 3rd by email. As far as I can tell, U of I has no official visit weekends. You just set up a time to meet with the department individually.
This forum is making me a little nervous about my chances at Caltech and Stanford. Does anyone here know the notification processes at these schools? i.e. Do they accept only the outstanding applicants early and then decide on the next tier after that? Do they decide on applications as they read them?