Google Has Beated Yahoo! in Alexa Rank

I had just noticed that Google is now ranked number 1 in Alexa and Yahoo! is on second position. This is the first time in my internet history to see something like this. Is it because of the change of popularity or because of the new Alexa ranking system? Previously Yahoo has able to maintain the rank because of the variety of services. Now Google is doing the same thing and some of it's services are more popular. I've read somewhere that Google has actually being owned by Yahoo therefore no matter who's on top, same people are getting the profit.

I wonder why my pagerank is still not updated. Does Pagerank and Alexa rank use similar type of algorithm on measuring site popularity?