So far, we still can’t make sure when Microsoft will push the Windows Phone 7.8. But if you have a Windows Phone device, then you can experience the customized Windows Phone 7.8 ROM first.
The Customized Windows Phone 7.8 ROM for HTC Surround from Lars of XDA-Developers has been released. It’s completely unlocked without bugs.
You can download here. http://forum.xda-developers.com/showthread.php?t=2080612