I have a Droid Incredible and interface with a OBDII reader via Bluetooth using a droid app called "Torque". It really works great. No probs at all.
So its http://www.engadget.com/2010/04/19/d...edible-review/ plus this http://uniquefindz.myshopify.com/pro...product-search plus this http://www.androidzoom.com/android_a...rque_flre.html
Does real-time readings and even can upload all data to a webserver for graphical display via any web browser. Amazing, I know. Its inexpensive too, as long as you have a droid. Its a poor mans (or smart mans?) scangaugeII, but with better interface and more features.