When filing a ticket about a USB device not working please include the information given by running the dmesg command. Some of the information from that command can be used to make the device mountable. Also be sure to include the make and model of the device having the problem.
Here's an idea of what's going on (from TicketID#20040908102049, "Fedora has no support for USB drives").
The kernel should have no problems recognizing a USB removable device. However, updfstab needs to be configured on a drive-by-drive basis. The USB device provides it's own description. updfstab uses this info to add an appropriate entry to the fstab so that users can mount these devices.
Currently, updfstab will configure devices whose description matches:
There's a package called tcc-updfstab which pushes the information kept in /etc/updfstab.conf.tcc to each of the clients. When a user reports their USB device is not working this file should be checked and if the device is not listed in it then info from dmesg should be used to create an entry. /etc/updfstab.conf.tcc is being rsynced off of update.nmt.edu at /var/ftp/pub/config_files/fedora/etc.