Waitlists are a real wild card, since they depend upon accepted students submitting deposits. I have heard stories of applicants getting called in the day before classes start to come off the waitlist when some admitted applicants are no-shows. The best thing to do is to keep in touch with the admissions offices of the schools where you are waitlisted to reiterate your interest and check to see what your status has become. Don't wear them out, but every few weeks would be an appropriate amount of persistence to demonstrate. Good luck.