Did Google Penalize Your Website Rankings or PageRank ? Read This
Google has confirmed that they decrease the toolbar PageRank of sites that sell links and pass PageRank without using rel=nofollow.
matt cutts
SEO Tricks from Matt Cutts at WordPress – No Black Hat SEO
The SEO and spam king at Google, Matt Cutts, gave a good talk on optimizing your WordPress blog for the search engines (especially Google) – he was speaking at the two day WordCamp 2007 conference.