Portable MP3 Player compatible w/ Linux?

I've been thinking about purchasing one of those portable MP3 players like
the Diamond Rio or the Nomad II. Has anyone ever heard of any portable
MP3 player working with Linux? We've got the USB support, so all we need
is the software that talks to the player for moving files back and forth,
right? I don't have any Windows boxes at home so I'd hate to have to
install Windows just to use the MP3 player...
I could always strap my laptop to my back and use it as an MP3 player, but
that's a little cumbersome, especially when I'm working out. ;-)
Thanks,
~M