... It is only for testing mersenne primes, and limited by memory to only being able to test primes up to around 2290000000-1... which would currently take about 245 days on a GTX460 (an exponent, which if my calculations are correct, would take about 19 years on a 2GHz single core CPU. The next Mersenne to win an EFF Cooperative Computing Award would be around 2336000000-1) ...
Ouch... Too late in the night for counting all those exponent digits... It is moving somewhat when you need exponents to sensibly express the exponents!
Quite a nice speedup there for the GPU to CPU comparison

Aside: I hit a RAC of over 200k on a test run with Boinc-GIMPS on my GTS450.
Happy fast crunchin',
Martin