Hi Golfman. In a nutshell Folding@home is a distributed computing charity set up by Stanford University scientists to aid in finding cures for Cancer, Alzheimer's, ALS, Huntington's disease and other protein misfolding related diseases.
On the PS3 (if you've got the latest system update) it's now called "Life with Playstation".
What it basically does is while your PS3 is on but isn't being used to play games or watch movies it will download a work unit and try to simulate how a particular protein folds. When its completed doing the simulations it will send the results back to Stanford for their scientists to collate and study the data.
It's got some pretty interesting features as well like a 3D globe showing news and weather from major cities in the world and a nice soundtrack to listen to (or put your own music on if you get sick of what it plays!).
It's a completely safe program (Sony wouldn't approve of it if they thought it wasn't) and I've been running it on my PS3 slim for about 3 1/2 months now.
GTPlanet has its very own Folding@home/Life with Playstation team and there's a dedicated thread for it (as Slims pointed out) -
https://www.gtplanet.net/forum/showthread.php?t=92758
I also made a really detailed post on F@h/LwP and its acheivements on this other thread -
https://www.gtplanet.net/forum/showthread.php?p=3946090#post3946090
Should keep you entertained for a while

. If you've got any questions just ask in any of the threads above or this one. I'm sure no one will mind

.