I'd love the UPnP media server to serve up Album art too.
(The remainder of this posting should probably live in the Development forum; but I'll press on anyway..)
I had a quick look at the output of the MC UPnP server...
The DIDLite is missing the <upnp:albumArtUri> tags for both tracks (object.item.audioItem.musicTracks objects) and their containing albums (object.container.album.musicAlbum).
Also, album "containers" should really be of type <upnp:class=object.container.album.musicAlbum> rather than object.container.
Fixing this would probably make the Album Art appear on the PS3 and some other devices that I use.
If the art is embedded in the file, then it would be up to the PS3 to display it. Perhaps the format or the size matters.
I believe the spirit of UPnP AV architecture is for the Media Server to dish up the Album art as a URI, irrespective of where it is stored, (eg Folder.jpg, database, or embedded>. This allows the UPnP control points to be "dumb" wrt codecs - ie, it means the control point does not need to understand and decode the multitude of media file types, just to extract the album images.
(My reference/test system includes the "PlugPlayer" UPnP control point running on a iTouch, which allows me to push items from MC UPnP server onto a Linn DS player/Roku Soundbridge).
Any improvements to the UPnP server in this area would be most welcome.