I can confirm also that DVBLink works in W8 after the registermceapp action mentioned earlier.
In my case, TV setup in Media Center hung at the "inspecting TV signal stage." This was fixed by manually installing the latest drivers for my Hauppauge TV cards (device manager incorrectly reported that the drivers were upto to date).
Subjectively, the W8 dvblink_server service seems much less cpu hungry than in W7 and thus I see no pixellation on playing HD, for example. I read somewhere that W8 cpu/memory management is a lot better than in previous versions.
I also read that MS are lukewarm about supporting Media Center in W8 - see this quote in ZDNet http://www.zdnet.com/blog/bott/media-center-will-be-in-windows-8-but-not-right-away/3860
by Windows boss Steven Sinofsky -
Our opt-in usage telemetry shows that in July, Windows Media Center was launched by 6% of Windows 7 users globally with the heaviest usage in Russia, Mexico, and Brazil (frequency and time). However, most people are just looking around; only one quarter (25% of 6%) of these people used it for more than 10 minutes per session (individual averages), and in 59% of Media Center sessions (by these 6% of users) we see almost no activity (less than a minute or two of usage). TV was the most common scenario we observed, and not surprisingly, traditional media (DVD and CD) are less common (and declining over time) than streaming and file-based content.
For sure WMC is an old style app, with a lot of redundant functionality (music, pictures, etc) that is now handled by metro style apps, so what we need now is a cool, clean metro TV app.... Anybody?