On May 27th, 2011 Google celebrated the great Arab Historian and sociologist Ibn Khaldun as shown in its logo above.
Ibn Khaldoun is most famous for his "Muqqadima" مقدّمة ابن خلدون. The great philosopher, who was born in Tunis in 1332 AD/732 AH and died in Cairo in 1406 AD/808 AH, is considered the father of modern historiography, sociology and economics. He is no doubt one of the greatest philosophers to come out of the Arab world.
The funny yet sad thing is that if Google hadn't commemorated Ibn Khaldoun in their logo, most of us would have never even known that today marks his birthday ...
Thank You Google!
For more information on Ibn Khaldun go to : http://en.wikipedia.org/wiki/Ibn_Khaldun