Microsoft has been preparing to update its existing Windows Phone 7.5 handsets to a 7.8 version before the end of the year. Though the update will bring the new Start Screen experience from Windows Phone 8 to existing handsets, it’s a known fact that Windows Phone 7.8 won’t be the Windows Phone 8 way. But it is still excited to finally get the chance to try out Windows Phone 7.8 for ourselves. You can keep on waiting to get your hands on an official release, but the custom ROM is out there, the very first Windows Phone 7.8 beta ROM.
This release has several warnings, so think carefully before proceeding. The ROM is based on a Tango 12180 dump from a Nokia Phone and very little testing was done before releasing this, so use at your own risk. There are no details like support for homebrew applications etc. for now, but can always re-flash your Phone with a WP7.5 ROM later.
XDA member Dotcompt has gone ahead and managed to port over Windows Phone 7.8 (early build) from a Nokia Phone to a venerable HTC HD7.
- # Version 7.10.8835.35
# Available only for HTC HD 7
# Windows Phone 8 Start Screen
# Not completely Tested
# The ROM is almost untouched, this means it is not fully unlocked or rooted and homebrew applications will not work (for now). It has only a few Deep shining customizations and
# You can always flash back a Windows Phone 7.5 ROM if you wish
Source: XDA [Download]