Google’s pointers on countering Web spam

Matt Cutts, head of Google’s Webspam team and an engineer who’s been working on the problem for eight years, offered some tips about combating it during a speech at the Web 2.0 Expo here.
• Use captcha systems to make sure real people, not bots, are commenting on your site.
• Reconfigure software settings after you’ve installed it
• Employ systems that rank people by trust and reputation.
• Don’t be afraid of legitimate purveyors of search-engine optimization services.