Apple released two sets of printer drivers on Tuesday, one for HP printers and another specifically for Canon laser printers. There doesn't appear to be anything special about either update other than bringing them up to date with the latest printers and under-the-hood stuff.
Patch notes for HP Printer Drivers v.2.16.1 for OS X:
This download includes the latest HP printing and scanning software for OS X Mountain Lion, OS X Lion and Mac OS X v10.6 Snow Leopard.
This update shows as a 499.82MB download from Apple's support site, but the version available through the MAS was only 82.7MB.
The patch notes for Canon Laser Printer Drivers v2.11 for OS X:
This update installs the latest software for your Canon Laser printer or scanner.
The update is a 28.82MB download through Apple's support site.
Both updates are for Snow Leopard, Lion, and Mountain Lion.