I wedged my system in the same way. SuSE 9.1, using the YAST print manager interface trying to add a new USB printer.
I'm not sure exactly how I got where I did, but I think I ended up starting multiple copies of the print manager interface.
What ended up happening was the system concatenated three copies of /etc/cups/cupsd.conf into a single entry. Therefore, there were three binds to socket 631, causing cupsd to barf and die.
I commented out the bottom two copies, resaved cupsd.conf, did an /etc/init.d/cups restart, and I'm back in business.
Of course, your mileage may vary.
Have a good day.