Here's my theory of what's going on:
When waitlist movement at a place like MSSM happens after June 1 or so, it is because someone who accepted an offer from them got in somewhere they'd rather go, so they let go of their MSSM spot. So, as long as there is ongoing movement at places like Columbia, Yale and Cornell (which there is), there is a good chance there will be movement at MSSM. The meeting that was held today was probably to pick through a few dozen applications and pick a handfull who would be offered spots in the eventuality that people start withdrawing. Those people may not be contacted for a good week or so, though, because then the spots need to open up. It may be that they've decided to hold the meeting because there are one or more spots already open, or simply because they anticipate them opening. In any case, I don't think anyone who doesn't get an e-mail from them by tomorrow should give in to despair. I know I won't. Good luck everyone!