Here is a workaround for putting subfolders on the PS3 that I found.
*You have to do this for every file.*
First select the file and press triangle, next scroll down to INFORMATION. Select it then scroll down to ALBUM (It's displayed right under the video's title) and press X. The keyboard will pop-up allowing you to change the album name to whatever you want (by default, the album name is always the date the file was copied over to the PS3). For example, I changed the album of all my movie files to "Movies" and I changed the album name of all my trailers to "T." Once you have done all that, press triangle on any file and scroll up to GROUP CONTENT (or press square) and select BY ALBUM.
Now all your files should be sorted into subfolders by album name. For example I have all my movies in a nice single subfolder labeled "Movies". I know it seems a bit tedious but it is an effective way to clean up the mess and organize your crap. This would work well for the guy with all the Family Guy episodes. This should work equally well for photos and music, though Ive got too many photos to rename.
