Google does not always play fair when it comes to SEO. For the longest time Google viewed SEO as wrong and evil. Actively seeking to manipulate search engine results was a no-no. Of course, back then Google wasn’t very good at spotting Black Hat SEO techniques and most search results were filled with less than relevant website results from spammers.
Today is a different day. Google now try’s to guide SEO professional and website designers to do what Google feels is appropriate in attaining good search results. To this effect, Google puts out guides and allows it’s Googlers to discuss tidbits of information about what Google likes in a website and what it does not. This information dangling tantalizes SEO professionals to agonize over every detail, trying to find the hidden meaning, the Easter Egg in the information.
If you have the time, I highly suggest you watch the video and read the comments and transcript from the Google I/O 2010 where the Google Search Quality Team answered SEO questions and reviewed websites and gave feedback.