Apple has posted the 7th Mac OS X security update of 2006, it is available by choosing Software Update in the apple menu or via direct download:

• For PowerPC Macs using Mac OS X 10.4.8
• For Intel Macs using Mac OS X 10.4.8
• For PowerPC Macs using Mac OS X 10.3.9

Details of the changes can be found here:

• About the security content of Security Update 2006-007

The update includes significant fixes for Airport, the Finder and other OS components so its probably a good idea to install it as soon as possible.