remember iAlertU, the "theft alarm" that you can
configure to go off when your MacBook Pro is moved (by unauthorized hands, that is), by making use of the Mac's motion
detector. It's a pretty nice idea, but it leaves Powerbook users out in the cold. Enter MultiAlarm.
It works in a similar way, but isn't limited to the MacBook Pro. The developer has promised some Salling Clicker scripts for it as well, so you can arm/disarm your Mac from your phone, Palm device, etc.
For some reason, the thought of a Starbucks full of wailing Apple laptops makes me happy.