rj87uk - 9:52 am on Mar 2, 2011 (gmt 0)
I still think that mostly this update was based on content, freshness, age, 'quality' and weight of the sites as a whole (rather than page by page). I think they will now go back and look at it with more emphasis on deep links & devaluing internal links so that a site carries less weight and so the good content can still come up while the rubbish gets buried.
Its when certain types of pages or websites get a mark against them (which could devalue out going links?) that I think would cause unknown SERP changes like we have just seen, Google should have spent longer in test mode before rolling this one out.