Every year, Google celebrates its birthday on a different day. The reason for this is answered in their FAQ: "The exact date when we celebrate our birthday has moved around over the years, depending on when people feel like having cake. "
I kind of felt like having cake in early September, but I am not Google. Alas, when I was offline for the Sukkot holiday, Google turned 9.
(Thanks to Danny for the picture.)
Happy 9th Birthday, Google!