The Omni Group has released a major update to OmniGraffle, adding support for iOS 4.2 as well as several other new features. OmniGraffle 1.4 adds AirPrint and multitasking capabilities that will allow iOS 4.2 users to print documents directly from within the app and maintain application state and perform tasks in the background. Support has also been added for storing and retrieving files on MobileMe iDisk and other WebDAV services as well as exporting…