http://www.seomoz.org/blogdetail.php?ID=1467

The comments and discussion are a must read for SEOs/Webmasters
GoogScore = (KW Usage Score * 0.3) + (Domain Strength * 0.25) + (Inbound Link Score * 0.25) + (User Data * 0.1) + (Content Quality Score * 0.1) + (Manual Boosts) – (Automated & Manual Penalties)

KW Usage Factors:

• KW in title tag
• KW in header tags
• KW in document text
• KW in internal links pointing to the page
• KW in domain and/or URL

Domain Strength

• Registration history
• Domain age
• Strength of links pointing to the domain
• Topical neighborhood of domain based on inlinks & outlinks
• Historical use & links pattern to domain

Inbound Link Score

• Age of links
• Quality of domains sending links
• Quality of pages sending links
• Anchor text of links
• Link quantity/weight metric (Pagerank or a variation)
• Subject matter of linking pages/sites

User Data

• Historical CTR to page in SERPs
• Time users spend on page
• Search requests for URL/domain
• Historical visits/use of URL/domain by users GG can monitor (toolbar, wifi, analytics, etc.)

Content Quality Score

• Potentially given by hand for popular queries/pages
• Provided by Google raters (remember Henk?)
• Machine-algos for rating text quality/readability/etc

Obviously, this isn’t a perfect summation of the algorithm by any means, but I have a strong suspicion that if we were to see the exact algorithm in perfect form, we’d see that a lot of these factors are strongly reflected in the weighting.Read on…