Apple pushed a new Apple TV update (5.0.1) today. Primarily a bug fix, the update addresses the following issues:

• iTunes previews - Previews for movies and TV shows from the iTunes Store can now be viewed in HD.
• AirPlay - Fixes an issue that caused some iOS apps to have trouble connecting via AirPlay.
• Home Sharing - Improves the reliability of Home Sharing connections.
• Netflix - Addresses an issue affecting Netflix login and navigation.
• Stability and performance - Includes fixes for issues affecting stability and performance.

You can update your Apple TV by selecting Settings > General > Update Software on your unit.