I just followed the instructions here to format my Kingston usb drive http://www.cyberciti.biz/faq/howto-format-usb-pen-drive/
Instead of ext2, I formatted the drive to vfat. I forgot to use the naming option when using mkfs.vfat (webpage doesn't mention it) and when I try to use mren I get:
sudo mren /dev/sdb1 KINGSTON
Can't open /dev/fd0: No such device or address
Cannot initialize 'A:'
Is there a way to rename the file system or do I just have to wait until the next time I reformat it?