The problem with the Internet is anyone can say anything and claim to have Proof or claim to be an Authority.
Certainly in Internet Marketing, it ain’t necessarily so.
Here are the main sources we rely on for information in this arena:

Google Webmaster Central
Official Google Blog
Matt Cutts (Google Spokesman) Blog
Webmaster World
Search Engine Watch
Search Engine Land

Note that this doesn’t mean the information on these is 100% reliable. But at least these sites rarely get way off the rails.