First of all, congrats on being wait-listed... I know it's not what you were hoping for, but SOM takes _lots_ of people off of the wait-list, and if they liked you enough to wait-list you, they like you enough to accept you. I'm not sure how the numbers work this year, but a few years ago, I believe that out of something like 2,000 applications, they interviewed around 200 and ended up accepting more than 125 to fill a class of 75 people. Things are different now, as the class size is bigger... that might work to your advantage.
(Disclaimer: I don't work for the university, and those are just numbers that I vaguely remember from back when I was applying in 1999. Things may have changed, and those numbers may not even have been accurate then... but they're all I've got. Hopefully, someone will chime in with more recent info.)
I'm not quite sure when people _start_ hearing, but I know that people have come off the wait-list as late as orientation week and I wouldn't be surprised if people were still trickling in in the first week or two of classes. If you call the Admissions Office at (856) 566-7050, Liz Torres should be able to give you some accurate info on the wait-list. She's very nice and will tell you whatever she can.
Anyway, good luck and keep hoping. You're in better shape than you think right now. If you have any other questions, let me know.
Bests,
Paige