No official announcement from Microsoft yet but if your in the UK you will have probably seen the new MSN Video Player tile showing up in the TV Strip. UK users may have seen this show up last year for a brief time but now its back with plenty of content.
There are loads of full TV shows (from MSN Video) including Classic Doctor Who, comedies, documentaries and other series (lots from the BBC). The UI is very slick and it integrates nicely with the rest of Windows Media Center. Installing it is simple just click on the new tile in the TV strip and start the install, after a 5mb download the addin is up and running (You do need the latest version of Silverlight for it to work)
The video quality is pretty good, its not HD but certainly watchable even on a big TV and the content is a good starting point. It’s nice to Media Center get an update with local content, take a look at the gallery bellow