I read up on some of the older threads and it seems like if you interview early enough (probably January and before), you can't be out-right rejected. If you aren't accepted, they'll just put your application aside and review you again the next month. To me this is similar to a waitlist, but I guess they call it more of a hold.
Later in the season, you can get rejected post-interview. I think you can also receive correspondence indicating you are "waitlisted" which would suggest they won't necessairly accept you unless someone withdraws from an otherwise full class.
Who knows tho...