Google got caught red handed doing paid links for its Chrome Browser download page, breaking its own T&C's, so demoted it's PageRank to 0 for 60 days

Matt Cutts (Googles SEO Public face) said that after the penalty period, Chrome's download page could be returned to its search good graces. "Someone on the Chrome side can submit a reconsideration request documenting their cleanup just like any other company would," Cutts said.
Google downgrades Chrome ranking after paid-link monkey business - Computerworld
Guess that answers the question, who polices the police, it's the police
