I have a few old MemoryStick (non-Pro) cards. They show up as /dev/msblk* (not /dev/mspblk*). With udisks 2.1.3, they're detected and can be mounted; however, I'm always prompted for authentication because udisks thinks the device is on a different seat than seat0. (This regardless of me adding ID_SEAT=seat0 to udev properties, etc.)
So far I've reached udisks_daemon_util_on_same_seat(), where "drive_object = udisks_daemon_find_object (daemon, udisks_block_get_drive (block))" returns NULL for reasons unknown, but I don't understand GObject enough to go anywhere further.