I’m surprised someone didn’t come up with this application a long time ago. This free security application called “Don’t Touch Me” and is for the HTC Touch HD, Diamond, and Pro. It sets off an alarm when the celerameter inside the phones is moved a certain distance. Once the alarm goes off, you click on a button to put in an access code that will deactivate the alarm.
You can change the distance the phone can be picked up before the alarm goes off (perfect for when you are at a party, and think people might be looking at your phone, but you don’t want them to walk off with it.)
You can change the type of alarm that goes off, and there are many to sounds to choose from. It probably won’t be long before Apple has a similar alarm (whether or not it will be free, is another story.)