Today on Google home pages worldwide is a special logo for the 118th birthday of Albert Szent-Gyorgyi.
Albert Szent-Gyorgyi was born on September 16, 1893 in Budapest, Austria-Hungary and died on October 22, 1986 in Massachusetts, United States at the age on 93.
Why does Albert Szent-Gyorgyi get a logo? Well, he was cited as the individual responsible for discovering vitamin C. He won the Nobel Prize in Physiology or Medicine in 1937 in part for that discovery. He was most well known for that discovery with discovering the components of it and the reactions of the citric acid cycle.
Hence the tropicana like Google logo on the Google home page.
Forum discussion at Google Blogoscoped Forums and Google Web Search Help.