encryptor:
I have a AC-to-DC 12V, 1amp rated wall-wart. With that plugged in to the barrel jack is it safe to draw 950mA from the 5v pin? :.
Probably not. The 12v feeds the on-board +5vdc voltage regulator chip that then feeds the shield 5V pin as well as whatever the board itself requires. The regulator I think is rated at 700ma max, but can be limited to even less due to the heat loss of from cutting from 12V to 5 volts. It's better from a maxium current capacity to power the board with 7.5 to 8 vdc as it will allow the on board regulator to run cooler at any current demand placed on it.
Lefty