Use 3.3 v pin to power an xbox 360 controller?

The controller uses 2 AA batteries, so it normally takes 3 volts. Are there any precautions I should take before trying it out?

Where is the 3.3V from? If from an FTDI equipped arduino, be aware it is only good for some tens of milliamps.
From the FTR232 data sheet: "Up to 50mA can be drawn from this pin to power external logic if required."

Ok, good to know. Maybe I'll start low so that I don't fry anything anyway.

UPDATE: I tried it out with the 328 and it works fine so far.