Howtoforge posted a guide about disabling the Touchpad when the mouse is plugged in

Hello all, hopefully this brief how-to will help others, this issue has been bugging me for years. I want the same capability in Fedora that exists in most recent versions of Windows -- disable the touchpad on my laptop if an external mouse is plugged in. Note that my how-to is a little hardware-specific regarding the actual disabling of the touchpad; I'll discuss that more at the end of the guide.

  How To Auto-Disable The Touchpad When The Mouse Is Plugged In (Fedora 13)