Apple has released driver updates to supply additional support for printer and scanner devices from HP, Samsung, and Brother. These updates are for OS X 10.6 and include all the printer drivers supported on OS X from the respective companies. Apple uses its Common Unix Printing System (CUPS) in OS X, that uses generic driver sets that are enhanced to support specific features and functions of individual printer models, so as new models come out Apple can more easily tweak drivers to work with them. The latest printer drivers can be found at the following locations:
As with all printer updates, if your printer is working fine then there is no need to update the driver. It is very likely that Apple has not offered any new features to existing drivers, so updating will only alter your current configuration and increase the possibility that something will go wrong. Additionally, if your printer driver needs updating, a smaller and tailored version of the download will be available to you via Software Update, so it may be best to check Software Update first. Installing the downloadable updates in the links above will install all the included drivers, most of which you may never use. If in the future you need a driver, then OS X will automatically download it when you install the printer.
Beside driver updates, Apple has issued an update for QuickTime in OS X Leopard, which brings the version to 7.7. This update requires OS X 10.5 or later and is a ~69MB download through Software Update. Unfortunately while Apple's support downloads site lists the update, the linked downloads pages for the new software points to the older 7.6.9 update so we cannot yet link to it from here. Apple's security updates page mentions that the update mainly is for security to prevent the execution of arbitrary code in specific situations when handling media with the QuickTime program.