Apple has released a couple of updates that are relevant to people running Boot Camp on their Macs, and for iMac systems. The Boot Camp update brings the version of the drivers to 3.0, and according to the Boot Camp updater Web page, it addresses some critical problems with the version 3.2 driver set. Therefore if you are running Boot Camp, then Apple recommends you install this latest update.
The firmware update for iMac systems will flash their Radeon graphics cards to a new version that will address a problem where the systems were hanging when performing some graphics manipulation tasks. Unlike other updates, firmware updates change the hardware configuration of the system and therefore have potential to lead to more-serious problems if interrupted. Therefore be sure when you apply the firmware update to keep your system attached to a secure and reliable power source, and do not interrupt it by forcing the system to restart, even if there are extended delays during the update process.
For people running the relevant systems, the updates should be available via Software Update, but they can also be downloaded from Apple's support downloads site at the following locations:
As always, be sure to back up your system before applying these updates.