SEOmoz posted the 2011 search engine rankings study they polled in 2011. The last time they did this was two years ago and it is one of the most comprehensive polls done to determine what SEOs feel the most important ranking factors are.
Rand from SEOmoz explained that they "aggregated opinions of 132 SEOs around the world with correlation data from over 10,000 results in Google."
I am not going to go through each piece here but you can at the SEOmoz blog.
Forum discussion at Sphinn.