1. Avoid hidden text or hidden links.
2. Don’t use cloaking or sneaky redirects.
3. Don’t send automated queries to Google.
4. Don’t load pages with irrelevant keywords.
5. Don’t create multiple pages, subdomains, or domains with substantially duplicate content.
6. Don’t create pages with malicious behavior, such as phishing or installing viruses, trojans, or other badware.
7. Avoid “doorway” pages created just for search engines, or other “cookie cutter” approaches such as affiliate programs with little or no original content.
8. If your site participates in an affiliate program, make sure that your site adds value. Provide unique and relevant content that gives users a reason to visit your site first.
These guidelines are nothing new, which makes you wonder if something else has actually changed, or if they have really just implemented a way of better enforcing these guidelines.
As with Google Panda, the actual results of the update appear to be that spam sites have been promoted and many quality sites have been smoked. The assumption is that a lot of blatant spam has been removed from the index, and additional tweaking is needed. We’ll see if that’s the case as things progress.