I've run out of ideas here; This is pretty frustrating.
Can anybody who can properly mount and access the files on their BlackBerry's MicroSD card over USB under Linux let me know what "mount" options are being used? Also, can you tell me what BlackBerry OS version you're using. In particular, I'd be curious to hear from any 8130 owners. The problem doesn't appear to be distro-specific; I encountered the same problem using a much older Linux distro than the Fedora 8 distro I use on my primary-use computer.