Seems to fix some of my WoW kernel panics. Been testing for months, includes fixes for Time Machine address book issues and other improvements, including the included notes:
The 10.6.4 Update is recommended for all users running Mac OS X Snow Leopard. It includes Safari 5 and general operating system fixes that enhance the stability, compatibility, and security of your Mac, including fixes that:
- resolve an issue that causes the keyboard or trackpad to become unresponsive resolve an issue that may prevent some Adobe Creative Suite 3 applications from opening
- address issues copying, renaming, or deleting files on SMB file servers
- improve reliability of VPN connections
- resolve a playback issue in DVD Player when using Good Quality deinterlacing
- resolve an issue editing photos with iPhoto or Aperture in full screen view
- improve compatibility with some braille displays