Lessons From Penguin Update - Follow The Rules
From Danny Sullivan over at http://searchengineland.com "The Penguin Update launched on April 24. It was a change to Google’s search results that was designed to punish pages that have been spamming Google. If you’re not familiar with spam, it’s when people do things like “keyword stuffing” or “cloaking” that violate Google’s guidelines." Bottom line, follow the Google Webmaster Guidelines . In other words, don't bite the hand that feeds you.