Microsoft have just put up an official page regarding all the info you need to know about the Windows Phone 7.8 update that's set to launch today. The update will be pushed out to all devices over the coming weeks, and it appears Lumia owners get first dibs, along with a few others.
The webpage reveals some of the new features in 7.8, which are what we've already known for sometime now. That's the new Start Screen, Colours and Lockscreen.
As of right now, many Lumia and some Samsung and HTC devices have received the update, however my HTC Mozart still thinks 7.5 is the latest software.