Apple has released the latest version of iOS 5, beta 2 build 9A5248d. The update has been pushed out to devs and may be downloaded from the Dev Centre by registered iOS developers.
One of the main new features is Wi-Fi sync, which Apple confirmed in their official release notes:
In iOS 5.0 beta 2, wireless syncing is now available for the Mac. It requires iTunes 10.5 beta 2 and OS X 10.6.8 or Lion. You will see an option to enable wireless syncing when you connect your device to iTunes with the USB cable. It is recommended you perform your initial sync with a cable after restoring your device.
Wireless syncing is triggered automatically when the device is connected to power and on the same network as the paired computer. Or, you can manually trigger a sync from iTunes or from Settings -> General -> iTunes Sync (same network as paired computer required). Be sure your device is plugged into a power source when performing Wireless syncs.
Please note that developers with beta 2 won’t be able to message users running iMessage on the first beta.
iOS 5 beta 2 can be downloaded from Apple’s Dev Centre.