It looks as though Google has started off something the industry has coined as the "Google Dance" again. Basically every now and again Google does a full update of its index on all of its servers. This usually has several side effects either the ranking on your site goes up, or you start to loose rank as Google works out less higher ranked sites are pointing at you than there used to be. I've lost 1point on my page rank however my wife has several blogs which have all gained page ranking points.  Maybe I just don't blog enough?