The digital pins on the Arduino give out a maximum of 40mA (milliamps). The 3V DC Motor requires around 500mA to operate at full speed and this is obviously too much for the Arduino. If we were to try to drive the motor directly from a pin on the Arduino serious and permanent damage could occur. Therefore, we need to [ch64257]nd a way to supply it with a higher current. We therefore take power directly from the 3.3v pin on the board, which takes its power in turn from the DC regulator on the board which takes power from our 9v Power Supply. A DC regulator is the larger black object next to the DC in jack and all it does is take the input voltage and reduce it down to 5v. It is good for 800mA of power, which is more than we need for our small DC motor
Anyway, what about using the 5V pin for "high power" applications? What is the max output current there when using external power? (I can't seem to find it on the Duemilanove page)
We therefore take power directly from the 3.3v pin on the board, which takes its power in turn from the DC regulator on the board which takes power from our 9v Power Supply.
3.3V output from integrated L.D.O. regulator. This pin should be decoupled to ground using a 100nF capacitor. The prime purpose of this pin is to provide the internal 3.3V supply to the USB transceiver cell and the internal 1.5k[ch937] pull up resistor on USBDP. Up to 50mA can be drawn from this pin to power external logic if required. This pin can also be used to supply the FT232R's VCCIO pin.
This is well known an not considered a "voltage regulator" - I still think it is a typo. One would not refer to the FTDI in such wording as the author above did.