Awesome work on this. A convert from TVersity here. Thanks!
The main reason I came over from TVersity is the lack of custom menu's in their media library, particularly the need to have a large library of music accessible via first letter/artist. Scrolling through a huge list is just too cumbersome in the PS3. Your media library has this feature, which is great (although I'm having issues with it in 10.51 and also 620 versions --- issue posted elsewhere).
My feature request is for the ability to select which folders are scanned and/or cached in the media library. For instance, if I have shared folders for photos, music and videos but only want to deal with a large database that needs to be regularly updated for music (videos and photos are already nicely organized by folders), then it would be great to have a select box (or boxes) for each scanned folder indicating where or not it should be cached when used, cached when scanned manually, both or not at all.