I recently got ahold of a PS3 prototype, model CBEH-F1501-B. It has a 500 GB HDD, a ribbon cable coming out of the case, and the firmware on it is 3.73. It appears it was previously used as someones personal machine. Doesn't appear to have any obvious debug features like a TEST would. Anyone know if there's anything cool about these units, or is it basically just a retail with a bigger HDD?
If you post a picture of this: http://www.psdevwiki.com/ps3/More_System_Information , I could tell you more about it.
Ahhh, alright, cool to know what the cable is for. Didn't know about that menu. I'll take a picture when I'm home.