The biggest problem with this 'undercover' software is that its going to need an Internet connection to be of any use.
So if i were a big bad nasty thief, then i would check the machine for anything interesting (password, bank details, social security number, etc). Then id reinstall the OS making sure to erase the existing installation, and there you go, a laptop free of charge, and isnt going to grass you to the police or its previous owner either silently or at the top of its voice.

Laptops are a big issue with regards to theft.
Simple things like this though can put off less patient thiefs.

So things like:

> Firmware passwording the machine (prevents you reinstalling the OS if you dont have the password)
> An internal GPS unit (rather pricey though from what ive seen)
> Using FileVault to encrypt all your personal data (it doesnt stop them nicking the machine, but might stop them stealing your personal details)

However, all of these can be broken. So anyone that really wants that data of laptop can get it.