From the 2nd page:
So we have an arms race: the crowd-hackers manipulating eBay and Yahoo and Digg and del.icio.us versus the crowd defenders — developers and other users who scrub scams out of the system. The University of Michigan’s Resnick is optimistic that the good guys will prevail, so long as they continue to build algorithms that smoke out the cheaters. “A good reputation system makes people more trustworthy,” Resnick says, “because word gets around if they’re not.”