Thiebaud is famous for his paintings of cakes and other everyday objects, and has been associated with the Pop art movement.
As far as Google's birthday is concerned, today's logo change solidifies the notion that Google's birthday is, indeed, September 27. Google had previously been unclear about the exact date, sometimes celebrating on September 7, although the Google.com domain was registered on September 15, 1997.
Although 12 years is a lot in the world of IT technology, the fact that a company has grown so huge in this time frame never fails to astound us. Happy birthday, Google!
Recent update from gmail blog: Updated Gmail app in Android Market