I'm on a wait list as well. Last I heard I was about 6 people away, but the class is just about full. It'll be a close call. We were numbered, so you can get an idea what your odds are that way (typically the PT dept will let you know how deep into the waitlists they typically go each year). I don't think prospective students were removed unless they sent back a card to the school with a check box marked indicating they would like to be removed from the waitlist.
I've put in a deposit with another school, and notified them I'd be attending, just to keep my bases covered. If I get in the first, I'll just notify the other school I won't be going after all, and I'm sure they'll dig into their own wait list survivors as a result. I think this happens pretty commonly in grad school (a law student/friend told me tons of people in his class did this to keep their options open).
I hope this doesn't go until two weeks before school starts, since I'd have to do some last second planning on my commute as well as putting the other school in a tough spot when I pull out. I'm also taking 2 classes (1 a prereq for one, the other a prereq for the other) instead of 1 currently because of this situation. It's a small sacrifice to stay available for both schools.