SEOMoz just released version 2 of its Search Engine Ranking Factors article. The content in the article is based on a survey of a number of leading and well known SEOs.
The content is truly great. If you want to get a fast primer on what matters most, and what matters least, you can do that quickly and rapidly. In addition, the summary of the most controversial factors is fascinating too. These are the factors which some SEOs thought were very important, and others thought were not important at all.
Also, many comments were written by the people who took the survey, and that information is included in the survey results as well. Some of the comments are fascinating too. There is a lot of value add in just reading those.
Bottom line, if you are looking for a fast intro to SEO, or even if you are an experience SEO looking to refine your craft, read the SEOmoz search engine ranking factors report.