The Google logo since May 6, 2010. The major difference in comparison to the previous logo (valid since May 31, 1999) is the reduced distance of the projected shadow behind the word Google and the change in color of the yellow "o" to orange.
Source: http://en.wikipedia.org. License: All Rights Reserved.
The Google logo used from May 31, 1999 until May 5, 2010, changing the previous logo's typeface and dropping its exclamation point. This is still used as a secondary logo.
Source: http://en.wikipedia.org. License: All Rights Reserved.
The Google logo in 1998, used until May 30, 1999.
Source: http://en.wikipedia.org. License: All Rights Reserved.
