Best of Google Webmaster Help videos

Over at SEOmozBlog, Dr. Pete informs that there are 200+ Webmaster Help videos on YouTube featuring Matt Cutts, Google's most visible anti-spam engineer. Occasionally, some Google secrets slip out during these videos. He watched 70 of the videos posted in 2010 & gathered some unusual facts. Excerpts -

Google does not use the keywords meta tag for ranking. Meta description still has value for other reasons
Cross-linking 3 sites probably isn't a big deal, but 30 or 300 could likely get you into trouble.
...footer cross-links are often low-value
Google does not guarantee that pages in your XML sitemap will be indexed.
Indexation has a lot to do with your authority and trust – an authoritative site will get more love from the crawlers, plain and simple
Matt (Cutts) says: "Most people can switch their IP address and never have any issue whatsoever."
As long as your domain name and hosting country stay the same, switching from one reliable host to another should have no SEO impact.
page speed...would be one of over 200 ranking factors.
Google makes a change to the algorithm on the order of ONCE PER DAY.
These changes may be batched and rolled out in chunks, but another video confirmed a number of roughly 400 algorithm changes in 2009.