Observant tweeter nametrader noticed that Facebook has been continuing its rise up the rankings and has recently unseated YouTube to become the 3rd most popular site on the Web according to Alexa's Daily Rankings yesterday. Take a look at the graph below showing the daily reach for Facebook (in blue) and YouTube.
Next up for Facebook? Google and Yahoo:
I don't expect Facebook to pass Yahoo (in Red) any time soon, but if the current trend holds Facebook could pass Yahoo by March of next year and may actually catch Google six months after that.