The update package installs the latest printer, fax and scanner drivers specific to the devices the user has installed. The driver update does not appear unless the 10.6.5 update has been applied.
For a system with an HP printer installed, Apple only delivers the updated drivers for HP devices, reducing the need for gigabytes of disk space to be consumed by irrelevant printer software.
Apple details the models supported in its latest driver update in a support document. The list includes printer software released as of November 3, 2010.
The update includes third party printer software for over fifteen brands of printers, in addition to general purpose CUPS and Gutenprint (formerly Gimp Print) drivers created by the open source community to support a variety of other, older or discontinued printers from over ten other vendors.
Apple acquired the code for CUPS in 2007, and continues to maintain the open source project for Mac OS X and other Unix and Unix-like operating systems including Linux and BSD.
Apple now maintains printer driver updates for Snow Leopard
One example print software package, for the HP Photosmart C7200 series, initially shipped with Snow Leopard as version 4.0, later updated by Apple to 4.0.2. The latest update brings the software for this printer to 4.2, the newest version HP offers.
HP's own website now directs users to obtain their software driver updates through Snow Leopard's Software Update, listing only a year old version of the company's drivers in a package that includes utility software and custom scanner software, and older versions for previous releases of Mac OS X.
Apple changed the printing architecture in Snow Leopard enough to require updated new printer drivers for existing devices, and announced that it would be updating user's printer drivers via Software Update at regular intervals instead of leaving users to hunt down their own driver updates.