If you visit Google.com today, you may notice a new logo on the home page. The logo looks like this:
The logo is to remember Samuel Morse who was born on April 27, 1791. Today is his birthday, and Samuel Morse invented Morse code.
We have several threads on the topic, many of them asking why is Google's logo broken. In fact, one asked why is Google's logo not fully loading?
Googler, Jamie created a Google Web Search Thread specifically to talk about why Google changes their logo on special days.
FYI, Google had a Google Braille logo back in 2006.