iTunes 9.2 is now available for Mac OS X and Windows XP/Vista/7. iTunes 9.2 is required to sync with iPhones and iPod touches running iOS 4.
iOS 4 is scheduled for release June 21st, 2010.
iOS 4 is compatible with iPhone 3G, iPhone 3GS, iPhone 4, and iPod touch (2nd and 3rd gen).
iPhone 4 is scheduled for release on June 24th, 2010.