From the Building Windows 8 Blog:http://blogs.msdn.com/b/b8/archive/2012/05/03/making-windows-media-center-available-in-windows-8.aspx
Given the changing landscape, the cost of decoder licensing, and the importance of a straight forward edition plan, we’ve decided to make Windows Media Center available to Windows 8 customers via the Add Features to Windows 8 control panel (formerly known as Windows Anytime Upgrade). This ensures that customers who are interested in Media Center have a convenient way to get it. Windows Media Player will continue to be available in all editions, but without DVD playback support. For optical discs playback on new Windows 8 devices, we are going to rely on the many quality solutions on the market, which provide great experiences for both DVD and Blu-ray
The media pack installs Media Center, but this implies that third-party software will be needed for DVD playback. VLC media player should do it for free.