Rand Fishkin of SEOmoz recently posted a presentation on slide share named The Evolution of Google's Rankings. It was from a presentation he gave in the Searchmetrics Partner Meeting a couple months ago.
The slides take you through what ranking factors are most important to Google over the years, based on Rand's experience. It is broken down as follows:
- 1999 - 2002 : On Page SEO & PageRank
- 2003 - 2005 : Anchor Text, Domain Names, etc.
- 2006 - 2009 : Domains, External Links, Quality Raters
- 2009 - 2011 : Twitter Social Data, Brands, User Behavior, etc.
In fact, the whole thing was posted on YouTube, here they are:
There is a thread at WebmasterWorld discussing the presentation. Most find it dead on, but as CainIV said, "I think this makes to look at in terms of aggregate factors that those interviewed believe are in play across a large number of genres."
Forum discussion at WebmasterWorld.

Comments:
Will Spencer
06/22/2011 09:13 pm
Proof?
Atlantis72
06/22/2011 09:21 pm
What a BS article, way to show your ignorance and lack of credibility.
Barry Schwartz
06/22/2011 09:22 pm
Can you be specific?
Atlantis72
06/22/2011 10:15 pm
e.g. anchor text was important way before 03. Also no mention of content quality, i.e. not having thin or duplicate content and how important that is more than so many other factors these days.
Barry Schwartz
06/22/2011 10:18 pm
Do you don't agree with rand. Okay.
Atlantis72
06/22/2011 10:38 pm
I agree with a lot of what he says, although a lot of it is opinionated.
Nasif
06/23/2011 12:29 pm
Google Ranking Evolution = A tough competition for webmaster
Blog Services
07/06/2011 06:38 am
I have observed that nowadays that social media is playing a big impact in rankings. That's why a lot have been investing their efforts in social networks and quality contents.
seoguruindia
07/12/2011 11:17 am
I agree with much of what he says, although many opinions. SEO Guru