The military has found quite a few applications for iPod Touch'es and Android devices, but now a security specialist wrote an Android app that takes advantage of the lax security measures around popular cardkey security locks at hotels and other places that lets you unlock them and locks them back after 30 seconds. If the security system is IP based, the app brute-force attacks the PIN, unlocks doors and relocks them, all with just the touch of one button. Check out the video after the break for a proof of concept.
The app is interesting, to say the least, but I wouldn't recommend more than trying to make your way into your dorm of your own hotel room. Network security may be lax, but trespassing will still get you into a bunch of trouble.
Source: Ian Robertson