I have just finished building a home server and installed the OEM version of Windows Home Server 2011 (Vail).

WHS11 is certified as DLNA compliant however, it is a poor DLNA server.
The only options for media sharing are "On / Off"

When attempting to play .avi files on my Samsung 58 inch plasma using WHS11 I get a small 17 inch box in the centre of the screen.
I have tried adjusting every setting I can find relating to aspect ration on the plasma.

Whilst I could try to troubleshoot the problem I decided to turn of WHS media sharing and install Mezzmo version

WHS11 is based on Server 2008 R2 core and Mezzmo installation was flawless.

I have tested folder monitoring on the network drives and playback of .avi and .mkv with no problems at all.

Behaviour is identical to the install I have had previously been using on Windows 7 64bit.
(fast forward and rewind does not work with all .avi files)

Happy to provide logs on specific testing to conceiva staff should they be looking to officially list WHS 2011 as supported.