I am bit late in wishing all of us boss...Google on their 10th birthday. Anyway this is what they says about the exact date on their website
"Google opened its doors in September 1998. The exact date when we celebrate our birthday has moved around over the years, depending on when people feel like having cake."
This time they brought back their search engine the way it was in January 2001. They are also their birthday to kickoff Project10tothe100, a project seeking ideas on how to improve communities, employment opportunities, energy issues, the environment, health issues, education, shelter and housing problems or anything else. Five final ideas will be selected, with Google pledging $10 million in funding to them.