What do we know (not what do we believe) about PageRank and its relationship to SERPs?
PageRank has some relationship to SERPS (in concert with 200 other ranking factors).
I think we know that - and little more.
PageRank is not related to quality or relevance of a site’s content so it clearly can’t be the most important factor for a given search, but it must have a integral place in the equation.
So how important is it? High importance, moderate, or low?
It is popular with SEOs currently to dismiss the value of PageRank and to assert that it is not related to SERPs. We can all point to competitive searches where lower PR pages outperform pages with higher PR. Matt Cutts often reminds us not to worry about PR, that it’s "only one of more than 200 factors."
And yet, here on Corporate Information - Technology Overview Google says (bolding mine):
What facts can we bring to the table on this question? I am not asking you to tell me what you believe or what you heard someone else say. I am asking to explore what we know. Please substantiate any assertions.PageRank Technology: PageRank reflects our view of the importance of web pages by considering more than 500 million variables and 2 billion terms. Pages that we believe are important pages receive a higher PageRank and are more likely to appear at the top of the search results.
NB: I know there is an important distinction between actual PageRank (which is continually updated) and Toolbar PageRank (which is outdated when pushed), but for the sake of discussion, I wonder if can we leave that issue aside?