Earlier today Apple released a minor update for Apple TV owners. HD iTunes Store previews have been added for movies and TV shows alongside several bug fixes and stability improvements.
Apple has released Safari 5.0.1, the latest version of its browser that adds support for the Safari Extensions Gallery and it includes a patch for the recently discovered Address Book bug.
According to Software Update on my Mac the update includes these new features:
Safari Extensions
Customize Safari with features created by third-party developers
Find extensions in the Safari Extensions Gallery, accessible from the Safari menu and extensions.apple.com