I have a wireless networking setup broadcasting at 802.11n (not b/g compatible) and my iPhone is able connect to it... I thought the iPhone
was wireless g?
I seriously doubt the router is not also supporting 802.11b and 802.11g.
Of course it's possible that newer iPhones are getting a better radio chip that includes 802.11n. N is where all other Apple products are going (if not already there!)