I've heard people say that one of JetBlue's problems is that they have been trying to grow thier fleet too quickly, unsure as to whether they'll actually be able to fill those airplanes. It seems AirTran has something like 100 airframes on order (not a small number), so aren't they doing the same?
And once those planes are delivered, I'm guessing you'll see people sitting in the right seat alot longer. Though it seems AirTran is not a bad place to be an FO.