There is a huge zipper running down the middle of the Google home page. When you click on the logo or pull down the zipper part of the logo, it splits open the middle of the page and reveals the hidden message behind the logo.
Here is a video of the logo, so you can see how it works:
That message is to honor the individual who invented the logo. The man is named Gideon Sundback and he was born 132 years ago today. He was born in Sweden on April 24, 1880 and died in Pennsylvania, United States on June 21, 1954 at the age of 74. He did not move to the U.S. until 1905 and married in 1909 to Elvira Aronson.
During that time he was working on the zipper. He worked on it between 1906 and 1914 and in 1917 the patent was issued and in 1914 it was filed.
This may be my most favorite Google logo - I kid you not.
Forum discussion at Google Web Search Help.