Per a MacNN link, Apple Licensed the Common UNIX Printing System:
CUPS provides a portable printing layer for UNIX-based operating systems. It has been developed by Easy Software Products to promote a standard printing solution for all UNIX/Linux vendors and users. CUPS provides the System V and Berkeley command-line interfaces.
CUPS uses the Internet Printing Protocol ("IPP") as the basis for managing print jobs and queues. The Line Printer Daemon ("LPD") Server Message Block ("SMB"), and AppSocket (a.k.a. JetDirect) protocols are also supported with reduced functionality. CUPS adds network printer browsing and PostScript Printer Description ("PPD") based printing options to support real-world printing under UNIX.
No indication as to when this will be intergrated into OS X.
