Yes, interesting Gareth, here's some more... Sep 15, 2009
Crop Circles - (Selected Countries)
Sep 21, 2009
H.G. Wells' Birthday - (Selected Countries)
Sep 05, 2009
Unexplained Phenomenon - (Selected Countries)
Aug 25, 2009
400th Anniversary of Galileo's First Telescope - (Global)
Jul 10, 2009
Birthday of Nikola Tesla - (Global)
Jul 20, 2009
40th Anniversary of the Moon Landing - (Selected Countries)
May 16, 2008
Invention of the First Laser - (Global)
And many more at.....
http://www.google.com/logos/logos08-2.html