I'm curious as to how it was determined they were one of the best when they hadn't written anything yet. It seems a lot of proposals with code and demos got declined (not even looked at in some cases) but in this case a proposal with no code, which has essentially already been funded and done by your group... gets an invite?
I don't know if they got an invite--we talked to them before any decision was made. But if they don't have a demo before the interview, I strongly suspect they won't get in--our pitch was not well-received by pg, and only the strength of our demo brought rtm and tlb around to an appreciation of the difficulty of the problems we're solving. And, we have yet to prove that this is a lucrative market--we know it is, but YC can't be blamed for not knowing it yet, since we've had no exit and growth is steady rather than explosive.
But, YC will fund groups that are working on the same problem domain, but not usually in the same round. Since we're a year in the past, I'm sure they wouldn't turn a team down based on where we are.