By law many cars now have a standard interface to access the engine management system. Unfortunately its still not that easy to actually get to the data.
The video above shows the ElmScan 5 Bluetooth wireless scan tool, which interfaces over Bluetooth with your smartphone and is said to have a range of up to 300 feet.
It supports all OBD-II protocols, features automatic protocol detection and interfaces with standard OBD software such as OBDKey for Windows Mobile.
Read more about the hardware at Scantools.com here.