I've heard rumors of someone scoring a 290, but who knows if that is true.
I think the score we get is a raw score. There are 350 questions total with about 50 questions being used for research. So theoretically there is a possible 300 score, but about 5-10 questions are usually omitted because of errors. So realistically 290 is the highest score possible under most circumstances.
That's my take on the whole scoring deal.