Along with refreshing its hardware lines, such as the iMac all-in-one and Mac Pro, Apple has also pushed out an update for OS X.
Version 10.6.4 contains some security fixes (which were previously released in June), along with some new bits and pieces targeted at smoothing over a few bugbears with the fresh range of iMacs.
It resolves some graphics related performance and compatibility issues, and adds support for the new Magic Trackpad, which is an option on the revamped iMac range.
Apparently the update also improves compatibility with large format SDXC memory cards. And that’s about your lot.