Can I upgrade to iPhone OS 4.0 on my original (2G) iPhone?
No. At this time reports have indicated that first generation iPhones (also known as 2G) will not support firmware version 4.0. iPhone 3G, iPhone 3GS and the fourth-generation iPhone hardware will all support the new operating system.
iPhone OS 4.0 has been described by some sources as making the iPhone act more like a full-fledged computer.
Rumors have also surfaced of a new hardware device that will run iPhone OS 4.0 and sport a 10-inch touch screen. Some application developers have already been asked by Apple to prepare versions of their software that will support the larger screen format.
Apple is expected to announce iPhone OS 4.0 on Wednesday, January 27, 2010.