Wirelessly posted (iPhone: Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_0 like Mac OS X; en-us) AppleWebKit/528.18 (KHTML, like Gecko) Version/4.0 Mobile/7A341 Safari/528.16)
Fixes some problems with extending and maintaining connectivity with extended networks
Fixes an issue with clients that enable 802.11 "Power Save"
Fixes connectivity issues with some third-party devices
Fixes an issue when the base station is configured for PPPoE
Fixes some Back To My Mac issues with connectivity and support for third-party routers
That is directly off Apple's support page. Thank goodness for copy/paste on the iPhone.