So, just to recap:
Subsonic/everything is running on a linux box, and the file with the "é" in its filename is on the same linux box, on the same disk as linux/subsonic/etc.
Here's what works:
* Playing the song directly on the linux box (e.g. opening up VLC, and using it to open and play the song w/out any interaction w/subsonic)
* Playing the song directly on a Windows box (e.g. opening up VLC on the Windows box, and using it to open and play the song, which is accessed via a samba share, w/out any interaction w/subsonic)
* Playing any song with "normal" characters in its path/filename, using subsonic, on the linux box
* Playing any song with "normal" characters in its path/filename, using subsonic, on a windows box
What doesn't work:
* Playing the song w/the "é" directly on the linux box, using subsonic
* Playing the song w/the "é" on the windows box, using subsonic
So yeah...maybe it is some weird Java interaction thing...if I could get more debug info out of subsonic (or even step through its code) that would help a lot...