I would like a folder sorting option too.
My use case : an 80's compilation where I want to keep the original album info for reference (track #, album, artist). I don't want to have as many "media player folders" as there are albums/artists in my compilation. I also have full albums, so I don't want to just list tracks, or the tracks for the full album would be scattered through the huge list (15GB of mp3, mostly 190kbps), and take a long time to find.

My DAP does this (Cowon D2), but my N900 is way less comfortable to browse through.