Matt Cutts of Google has written two posts on the topic of SEO:
The first, Detecting more “undetectable” webspam, should trigger some heated comments at his blog. It shows how he was able to find what was claimed to be “undetectable” cloaking and web spam. Matt then issues his warning to webmasters:
More generally, if someone is trying to manipulate Google by deceptive cloaking, it means that a webserver is returning different content to Googlebot than to users. That’s a condition that can be checked for by algorithms or manually, and such cloaking is certainly not “undetectable.” For cloaking to be completely “undetectable,” it would have to be like that Steven Wright joke: “Last night somebody broke into my apartment and replaced everything with exact duplicates.” And a cloaking script that gave users and Googlebot exactly duplicate pages would be a bit pointless.
There are currently over thirty comments at Matt’s blog, I assume you will be able to find over a hundred by the end of today.
In Matt’s other post, The anatomy of a search result, he breaks down how the search result snippet works. He describes in the video below each of the following components: the title, the description, the plus expansion box, the URL, how Google bolds keywords, the cache link, similar pages link, and, Google notes, Site Links and the more results link. Here is the video: