Microsoft officially announced the eagerly awaited Windows Phone 7.8 update is going to see the day of light in early 2013In the announcement at its official blog, the company re-confirmed some of the new features that will come as a part of Windows Phone 7.8. The new available colors for the UI theme were mentioned (over 20 new color). The additional Exchange security enhancements and ability to resize the Live tiles were also revealed, but are nothing new.
We know you're eager to get the Windows Phone 7.8 update, and we want you to know that we're working closely with our hardware and carrier partners to get it tested, approved, and rolled out to as many devices as possible in early 2013. As we work to quickly get this in the hands of our loyal users, we're also striving to deliver a high-quality release and ensure a smooth transition for our widely expanded services. - Windows Phone Official Blog