When visiting the Common UNIX Printing System website, there is a short news entitled: "CUPS Purchased by Apple Inc.". While the news was published on July 11th, it seems that the deal was settled down at the beginning of this year:
Created at 14:49 Jul 11, 2007 by mike
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 is used by Apple in OS X for managing printing and files queuing.
[translation by Linathael]