Ever since the Florida Update SEO and SEM firms have been speculating on what Google did and why they did it. We developed our own theory in which we believe Google used some of the Applied Semantics technology to build one of the world's largest ontological databases. In other words Google has been attempting to infer meaning on pages, and returning results matching or similar to that meaning.
While others dispute this and say the results are because of other algorithms, like the 'Hilltop' algorithm (which has many of the same parts of the ontological algorithms built into the Applied Semantics package) none dispute the fact that November 2003 was a turning point for Google.
It was also shortly after this happened that many began to realize that PageRank was playing less of a role in the overall rankings. Who would have thunk that Google was now saying "regardless of the PageRank sites that more closely match the query would be returned in the results?"
This led many to speculate that PageRank was dead and that we no longer need to focus on PageRank as it has little to no effect on final rankings. However, I'm here today to tell you that this isn't entirely true. And the reason I think this has to do with how Google, the physical system, works.