It appears as though all references to AirPrint have been removed in the iOS 4.2 gold master release notes, despite the initial release notes stating that it was included. Also, on the Apple Developer Forums, one developer claims that an Apple Tech Support agent has told him that "support for AirPrint on Windows and Mac has been cancelled."
Source: http://itsalltech.com/2010/11/09/airprint-functionality-cancelled-in-ios-4-2/
Thoughts?