My two cents (take them for what they're worth, which may not even be two cents)
My son is a freshman MT at UMich. I believe this year the department is being a little more cautious sending out acceptances because last year they did end up with more students matriculating than they anticipated. The current freshman MT class is 24.
The department will not complete their offers of acceptances prior to the completion of the auditions the weekend after this one. So once again, if you have an audition scheduled, go for it!
As far as using Facebook as a source for the number of students who have been offered acceptance, I'd recommend proceeding cautiously. According to my son, last year there was one or two students who joined the Michigan MT 2012 Facebook group who later were found to have not been offered a spot after all.
Lastly, this weekend is the 25th Anniversary Gala. I'd imagine it is a very busy time for the department and I'd be surprised if any acceptances were offered for the remainder of the week.
Good luck everyone!