Apple Security Update 2007-005 (Universal)

I just installed this update, and after two reboots and a rather long wait to get to the login window, none of my hardware controls worked (brightness adjustment, etc.). I tried to shut down, and my Mac hung after closing all the UI elements and Finder. However, a hard reset and a reboot brought it back to normal.

Security updates for OS X can be a little weird; I guess this one is just weirder than usual.