A new posting at Cups.org reveals that Apple has purchased CUPS and hired its author:
In February of 2007, Apple Inc. acquired ownership the CUPS source code and hired me (Michael R Sweet), the creator of CUPS. CUPS will still be released under the existing GPL2/LGPL2 licensing terms, and I will continue to develop and support CUPS at Apple.
CUPS stands for Common Unix Printing System and was adopted by Apple in 2002 for Mac OS X. CUPS is also heavily used by Linux distributions for printing services.
Other FAQ articles posted at Cups.org clarify trademarks, support, features and license exceptions.