My friend and I developed a game for the iPhone which was just accepted yesterday. It was quite a process that took us about 2 months R&D and then another 2 months to develop and polish it, and finally 6 days for them to accept it.
Granted this was all done our spare time so it's hard to truly estimate the total development time.
I've seen some questions pop up from time to time around here about iPhone development, so I'm more than happy to answer any questions about the entire process.
*Edit - Strange, hotlinking doesn't seem to be working. You can see the game here:
http://www.monkeywrenchgames.com/