US iPhone supports WIFI Channels 1-14
Not anything particularly significant. But being in Japan my Airport Extreme N supports channels 1-14 vs 1-11 for the US version.
My MacBook Pro 17, being purchased from the US supports channels 1-11 so I had to lock my base-station to any channel between 1-11 so it works with US WIFI devices. And no, you can't just change regions it doesn't work I tried.
Anyway, I recently swapped my WIFI card in my MacBook Pro with the one that is shipped inside the AppleTV which was a Japanese version so it supports channels 1-14, cool.
But of course I thought I was still limited to channels 1-11 if I wanted my iPhone to work. So I decided to try channels 12-14 on the Japanese band and to my surprise the iPhone supports the extended channels which in the past has been locked out depending on where the product is sold.
So just an interesting side note that channels 1 - 14 are fully enabled on the US version of the iPhone.
Now technically it is not legal to use channels 12-14 from what I understande in the US but I suspect since the iPhone is not creating the network it can certainly listen to those channels in order to initiate a connection since it is not transmitting initially.