Apple released its major update to the Apple TV OS Friday, following up on the fanfare promised in the latest round of product releases. But it seems the fanfare turned nasty, as many Apple TV users reported that their Apple TV units became inoperable after having the 6.0 update installed. In response, Apple pulled the update, advised those with problems on how to do a factory reset, and said it would try again once they'd fixed the problems.
The update was designed to fix a number of security bugs, bring the new iRadio service to Apple TV, and shift several old networked services to iCloud.
Source - Apple TV Update Withrawn After Complaints, InformationWeek Mobility