Apple released a few updates for Canon, Brother, Lexmark, and HP printers. These updates contain the latest drivers for printers and scanners from these companies, so if you have a printer or scanner that is giving you problems you might benefit from installing them.
The updates are available at Apple's downloads page:
Lexmark Printer Drivers for Mac OS X v10.6 - 117MB
Brother Printer Drivers for Mac OS X v10.6 - 99.9MB
Canon Printer Drivers for Mac OS X v10.6 - 274.59MB
HP Printer Drivers for Mac OS X v10.6 - 387.44MB
More information on these updates and printer software for OS 10.6 can be found in this Apple knowledgebase document: http://support.apple.com/kb/HT3669
If you do not have any problems with your current printer driver and are able to print just fine, then I would recommend you do not apply these updates; however, they are available in case any problems do crop up.