It looks like it’s someone’s birthday but whose?
Google’s 6th birthday!
Browsing through Google’s holiday logos I noticed that last year Google celebrated their birthday on the 7th of September (today), but in 2002 they celebrated it on September 27th. A possible typo, though there are no other references to their birthday on the page.
All of the Google’s logos can be found at google.com/holidaylogos.html