Eldar Murtazin, the editor-in-chief of Russian mobile phone blog Mobile-Review today tweeted that iOS 5 will not be compatible with the iPhone 3GS, limiting the new operating system to the iPhone 4 and the next released model. Just one comment. Apple iPhone 3Gs wont be upgradable to iOS 5.x. iPhone 4 will. It is unclear where Murtazin obtained the information, but he has a very solid reputation on the mobile phone rumor mill. iOS 4 was released last June and was compatible with the iPhone 3G,3GS and the iPhone 4, although all models were not compatible with all of the features. Apple finally discontinued support for the iPhone 3G with the release of iOS 4.3, leaving that device at a maximum operating system version of iOS 4.2.1 pretty much making it obsolete.