This info may be a bit outdated. Granted, I matriculated at Michigan in 1998. From what I know, Michigan has 170-180 spots per year. Michigan will only send out that many acceptances; no more, no less. Michigan is not like other schools that send out twice the number of acceptances in the hope that half of the students will matriculate and fill the class.
So, if you are on the waitlist, it is hard to conclude anything unless you know exactly where you stand on the waitlist. I don't think Michigan tells you this information.
Here is a story which some of you may appreciate hearing. My roommate was all set to go to UC Irvine for med school. He was on the Michigan waitlist for what seems to be an eternity. One week before orientation started at Michigan, he gets off the waitlist. He has to pack up and cancel all his **** at Irvine and move his ass here. I only tell you folks this story because you never know when you'll get off that waitlist. Some may get accepted off the waitlist early, some really late, some never. You never know.
Best of luck y'all!