BSD - Drop me a message when you pick your dates, and do the lunch program. I know folk who do that.
I don't know for a fact why they do the wait-list thing, but I have a feel for how it works. You lose either way - either you start hearing people who applied later getting invited to interview while you are "under review", or you get told straight away you are waiting. It is tricky and different schools operate different ways. I think they like to be on the level with people as soon as possible - you have lives to live, offers and other applications to think about, and some news is better than no news.
At Stern you will interview before you can get an admit. The interview percentage is reasonably low. They mentioned today that they have a very big upswing in applications this year, so I know they are trying to manage a pipeline. They don't like to make decisions purely on Stats (I know that for fact), so each application goes under review pretty fully (I expect).