igvita.com has a story "Collaborative Map-Reduce in the Browser" about using http and browsers running javascript on a large number of machines to solve map-reduce problems. The size of such a system might dwarf Google's facilities.

http://www.igvita.com/2009/03/03/collaborative-map-reduce-in-the-browser/

slashdot:
http://tech.slashdot.org/article.pl?sid=09/03/03/1910207