http://www.zdnet.com.au/newstech/enterprise/story/0,2000025001,20267287,00.htm

"Cluster computing is about resources aggregation in a single administrative domain," he (Rajkumar Buyya) explains. "Grid computing in about resource sharing and aggregation across multiple domains."
I have no idea what that means,however ..."Having recently completed a doctoral thesis outlining the economic paradigm which might underpin such a system in the commercial environment, Buyya points to the Grid's scheduling capabilities as the most crucial difference between grid and cluster computing."
Oh and get your old MMflash off,soon,so I can get in.