Last week, Matt Cutts told everyone at SMX Advanced that Google has updated its SEO documentation. He blogged about the changes on his own blog. There's new documentation on the robots.txt protocol, how Google accounts for user feedback, issues revolving around IP delivery and cloaking, updates to nofollow, and more. Matt also is quick to note that web pages should be designed primarily for users, because the lack of the word "primarily" used to cause confusion. Finally, Google has defined doorway pages as such:
Doorway pages are typically large sets of poor-quality pages where each page is optimized for a specific keyword or phrase. In many cases, doorway pages are written to rank for a particular phrase and then funnel users to a single destination.
Useful information. Matt goes through the details and you can comment on his post or on the Sphinn discussion for more.