i had a strange issue with cups and gutenprint today, but found an rather unusaul solution.
i have an mpx280 printer from canon, but system-config-printer refused to find drivers for canon, althoug i have them installed and would freeze.
so after many hours of swearing and offending all gods that may exist, i had a feeling, i downloaded the .deb file for the driver from canon website, and extracted the deb file.
then i got to kde printer settings, choose manually add .ppd file, choose the .ppd file from the unpacket .deb file, rebooted and viola, printer working.
i think the issue of cups not detecting drivers arrose after latest update, i had an old arch install in vb, i could add and remove printers, then i updated that install, and i could not add printers anymore.
so i think its a bug either with cups or gutenprint.
i thought i would search first and do whatever possible solution before i ask for help on the forums or g+, so if you have problems with your canon printer, maybe this solution could help you