An update for the Apple TV (the second generation model) is also available that adds wireless mirroring functionality over AirPlay. AppleInsider: Apple releases iOS 5 for iPhone, iPad, iPod touch & Apple TV
Several updates to Apples iOS apps (Pages, Numbers, Keynote) are also available that add several features, notably support for iCloud. There's also an update to iMovie, though Apple doesn't list any major changes in Version 1.2.2 in the iTunes description:
This update addresses minor issues and expands support for videos imported from external cameras.MacRumors: Apple Updates iMovie and iWork for iOS, Remote Apps
Speaking of AppleTV, the current version only support 720p; could a 1080p version be just around the corner? A recent article on MacRumors hints at a possible 3rd generation version in testing and development, but concludes that any model could be as much as eighteen months away.
MacRumors: Next Generation Apple TV References Found in iOS 5, But When?
[UPDATE] The following article at MacWorld lists a few other features added to Apple TV in this update: Apple TV 4.4 update adds Photo Stream, NHL, and more