everyone, it's true that the interview process has been in full swing for quite some time, but it's still too early to throw in the towel. i know of *plenty* of med students who didn't get interview invites at certain schools until march or april and were later accepted. the timeline for available interview dates varies very widely by school; while it's true that at some schools, receiving an interview invite NOW leaves you with available interview dates only in april or so (i.e. pretty late), i just got an invite at one school and managed to schedule an interview for two weeks from now. so it varies. plus, as others have mentioned, don't forget waitlist movement starting in june--many, many people don't have an acceptance in hand until the summer. the march 15 deadline *only means* that a school has to offer AT LEAST enough acceptances to fill its class (NOT that they can't keep handing them out), and since many people hold on to multiple acceptances for a long time, that leaves PLENTY of open spots for people with no acceptances.
being on hold isn't the desperate situation that people seem to think. it basically just means that the adcom didn't want to interview you right away, but that you were too competitive to reject outright. this is NOT a bad thing! it's never over until you have a rejection letter in hand, so until then, consider yourself very much still in the game.
what if you don't get in this year? well, you decide what you need to fix in your application, you fix it, and then you apply again. remember that 2/3 or so of all applicants don't get in *anywhere*, so not getting into med school is way more common than being accepted and you shouldn't consider yourself inadequate if you don't manage to get in this year. don't let the process defeat you. i've said this on this board many times: persistence is what matters most in getting into med school. i know it's hard to see the big picture when you're worried about how you as an individual will fare in the application process, but if you want it enough, you'll get there.
good luck to all of you, and keep your chin up!!
sandflea, who's been there