Its Official. Microsoft at Windows Phone Developers Summit announced no WP8 upgrade for the existing Windows mobile handsets. According to Microsoft, updating the firmware doesn’t mean like they will support those features as in, if Lumia 900 got the update but still it doesn’t have the hardware to actually exploit those features so what’s the use.

Instead, Microsoft plans to upgrade the current 7.5 to 7.8 which includes core updates. “When you pull that Lumia out of your pocket after you’ve received that 7.8 update, it will look and feel the same as a Windows Phone 8 device,” claims Sullivan. “Because you don’t have a multicore chip and don’t have some of these other elements, it didn’t make sense for us to make those investments for devices that couldn’t really exploit them.”
The 7.8 Update will have new startup screen, the tile customizations and what else in UI is there as mentioned they haven’t revealed all the features today. Windows Phone 7.8 update will be delivered to all Windows Phone users, bypassing the carriers both via PC and OTA.

For all the new features on Windows Phone 8 go here.