I was contacted by Dr. Smith in the Cognitive/Behavioral Neuroscience program in late January and came to visit this past weekend (March 5th). I was informed during the visit about acceptance. However, I was not attending a "visitation weekend" so it is likely that different professors have different protocol. The admissions committee met Tuesday to do rankings and make decisions (for neuroscience) but my paperwork was being held (rather than mailed) -- in the event we did not get along.
I visited during Spring Break so I didn't really have an opportunity to meet many people outside of this specific program.