I think wait list is the wrong way to put it (makes it sound too much like they aren't accepting people and you have to wait to hear) - it's more like a clogged pipeline. You get a start date, which may be sooner rather than later. Basically, Academy and ROTC guys all finish around the same time, and OCS people come through all year. So the system gets a bit jammed up at times.
From what I've been able to gather, they took more people than normal for pilots from OCS on the last board, and the last two boards both complained that they had to take applicants of a lower quality than they would like. Also, they are pushing out some of us who went to the December board to OCS in Jan and Feb, which is really really really fast.