Blast from the past
 

[url]http://arstechnica.com/civis/viewtopic.php?f=20&t=108573[/url]

It seems msft wasn't the first to think about porting Glucas to CUDA.

Edit: The above links to [URL="http://science.slashdot.org/story/08/08/27/2220226/45th-known-mersenne-prime-found"]this[/URL], which also has some GPU discussion.