Hello everyone.
Iīm very very interesting in this topic :-D
I will explain.
I have a xbox360 with a usb disk in HFS+ format. The video library is very,...., "sad" ? only have text. BUT If you copy a cover art into the usb disk and rename ever cover with the name of a video,....ufff, like this:
video1_name.wmv --> video1_name.jpg
video2_name.wmv --> video2_name.jpg
We will have a video library with cover arts. Text and picture. It isnīt a XBMC but it is more "human"

BUT
If you have an ethernet disk like Lacie, W.Digital,.... (NAS) with a Media Server embed you will have probabily a problem.
In my case, I have a new W.D. MyBook (White Light) disk. Itīs great, itīs fast, itīs silent,...and it has a TWONKY MEDIA SERVER installed. (4.4.9). Well, when I open the media library in the 360 the cover arts are missing :'( :-( WHY ?? I donīt know.
How can I solve this problem??
I think that the problem is in the Twonky Server, it doesnīt stream video and photo simultaneosly, ... xbox doesnīt "capture" the thubmnail by ethernet,...., a problem with the "thumbnail.db" file, ....
I donīt know

Itīs very important the covers, because the video library without them is very sad and poor.
I asked in the Twonky forumns and I didnīt have a answer.
I will like to know what need the xbox360 to paint the covers, ......
Excusme my english.
Thanks and regards!