Current line of Windows devices won't get Windows Phone 8 but 7.8
After the launch of Windows Phone 8, Microsoft confirmed that not a single smartphone out right now, not even the Lumia 900, will be able to upgrade to Windows Phone 8. The hardware requirements for WP8 preclude its running on any current WP device. After all, how can single-core devices with WVGA screens take advantage of multi-core and additional resolution support? That part makes sense, but if you’re a recent customer, you might be frustrated.
To keep its existing user happy, Microsoft has launched the Windows Phone 7.8, few software benefits will be included in WP8, and a hearty helping of these killer features (such as the new Start screen) will be available to legacy devices in the form of Windows Phone 7.8. There’ll be support for three tile sizes, with the smallest being fingertip size (a quarter of the standard square). The update will be delivered directly to users, sidestepping carriers, and can be done over WiFi.