Stephen Reilly wrote:
Most of those upgrades were small security fixes. There were two upgrades to the actual OS which actually added features/user interface elements, as I recall.
Upgrade 1: Added YouTube integration, slideshow screensaver, parental controls, photo priority and browsing other iTunes stores
Upgrade 2: added iTunes photo streaming
Upgrade 3: Added the ability to get content directly from the iTunes Store instead of via a connected computer, allowing users to rent standard and HD movies with Dolby Digital 5.1 surround sound and buy TV shows, music and music videos. Content automatically syncs back to the user's computer. Directory of over 100,000 video and audio podcasts. View photos from .Mac and Flickr galleries. Play iTunes content on the audio system connected to the Apple TV via AirTunes, limited Internet radio support, show everything or only synced content, TV show display tweaks, iPhoto events, and enhanced parental controls.
Upgrade 4: Added Movie Wish List, Support for Remote application, AirTunes receiver, Photo browser, MobileMe protected albums, Podcasts browsable by video and audio
Upgrade 5: Added HD TV shows, Movie browsing by actor and director, Chapter selection, alternate audio and subtitles, Movie description, Genius playlists, On-The-Go playlists, Music videos in playlists, Apple TV standby mode
Upgrade 6: Added AirTunes Streaming from Apple TV, Third-party Remote Controls, Playlists, Music Volume Control
Upgrade 7: Added Network Test
Upgrade 8: Added remote app directional control, Flickr Search, New view options, Updated transport and chapter modes
Upgrade 9: Redesigned user interface and compatibility with Apple's iTunes LPs and iTunes Extras, as well as Genius Mixes and Internet radio. Added Events and Faces support from iPhoto