This month is Gay and Lesbian Pride Month and Google is showing their pride by adding a rainbow to the search box for some search results.
For example, search in Google for [gay] or other related searches and you will see a rainbow on the right hand side of the search box.

Google also had this in 2008, but used a rainbow colored separated bar between the free and paid results.
Google is known as a company that is very gay and lesbian friendly. In fact, they came out with a controversial commercial about Gay rights.
That being said - it is Gay and Lesbian Pride month and Google is doing their part to bring it to light.
Forum discussion at Google Web Search Help.

Comments:
Oba
06/20/2011 12:48 pm
Good they don't have a pride year...
David Wilkinson
06/20/2011 03:26 pm
This isn't all search results - just LGBT specific ones. Quit yo' whining, fool! Funkyness FTW!
Zrafferty
07/06/2011 06:33 pm
god made adam and eve not adam and steve
Angus55535
07/26/2011 03:29 am
jackoff
Irish Verde Mundo
09/01/2011 01:06 pm
We should accept these people. They're part of our society. Let's not hate each other. Make love not war. registry mechanic