G'luck, ladies & gents!
I am well-versed with the waitlist blues. I played the application game two cycles. I won the privilege of being waitlisted at two programs my first year and at two programs my second year, so I am all too familiar with the waiting game that follows. However, it IS possible to be accepted off the waitlist. It happens more often than people think (even though I was extremely pessimistic about the whole mess at the time). I received that fated email on March 09, (I also know that my program has extended offers on the very last day possible in years past), so although it may seem late in the game right now, don't give up hope!
I know my program still has outstanding offers with its initial applicants, as I'm sure may be the case with other programs. As those folks respond to their offers, additional offers may be extended if they decline them for other programs. Again, don't give up hope, and try to keep yourselves occupied (as hard as that may be!).
G'luck to all!