MacStories.net is reporting that one of their sources working close with AT&T revealed that Apple will release iOS 4.2 on Friday at 10AM PST for the iPhone, iPod touch, and iPad. MacStories is also reporting that tomorrow will see the release of iTunes 10.1 and Mac OS X 10.6.5 via Software Update. Both iTunes 10.1 and Mac OS X 10.6.5 are presumed to be required for the iOS 4.2 update for its AirPlay and AirPrint functionality.
Last week the Gold Master of iOS 4.2 was released to developers and just last night a new version of Mac OS X 10.6.5 was seeded to devs. Apple had previously stated that iOS 4.2 would be released sometime this month.