While we spend the next few days wondering where we're headed, the umatched begin the scramble today at noon. Good first-hand descriptions of the process are available on the Student Doctor forums.
In my chosen field of emergency medicine, as of this morning, there were just 24 unfilled spots, out of 1188 positions in over a hundred U.S. programs. It's not yet clear how many people applied to EM, though some estimate around 1400 med students this year.