The Google Florida Update, unarguably the most talked about update in search engine history, generated several dozen theories as to Google's motives behind the update. 'Experts' from around the world quickly began analyzing Google results and historical facts to determine what Google's logic behind ranking one site over the next.
There are many famous theories but the two theories that have support from the majority of the well known SEO experts are: Dan Thies' Topic Sensitive PageRank (TSPR) theory and Phil Craven's Expert System Theory
The forums are buzzing with supporting facts and questions on these two theories. At Phil's SEO Forum, Phil and Dan discuss both their theories and how they relate and differ from each other. In addition, the thread discusses additional supporting evidence and clarification of the theories.
Very exciting and interesting information. I recommend you all read the theories and the threads.