Update: The big feature here is WiFi Sync!

• iTunes 10.5 Beta 2 CANNOT sync with devices on iOS 5 Beta 1
• iMessage seed 2 will be unable to communicate with iMessage users on seed 1.
• NEW: WiFi Sync! 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.
• Wallpapers are back
• New iCloud icon in Settings
• WiFi Sync must be activated in iTunes first
• Power source required for WiFi Sync
• Apple logo animated on first start up
• “No New Notifications” now in Notification Center
• Stock widget now off by default
• “it is recommended that you do not use the iCloud services to store any critical data or information.”
• “During the iOS 5.0 beta period, any documents stored on the servers might be purged periodically before GM. Therefore, it is highly recommended that you do not store any critical documents or information on the servers”

iOS 5 Beta 2 has just been released in Apple’s Developer Center along with Beta 2 versions for iTunes 10.5, Apple TV2, and XCode 4.2 Developer Preview 2:

Stay tuned as changes will be noted soon…