Every year for Gay Pride Month, Google has dressed up their top bar, like they do for the year-end holidays, with rainbow colors. This year, the colors are much more vibrate.
So when you search for [gay], [lesbian], [homosexual] or related terms and you will see this new top bar, for the month of June.
Here are the previous years top bar, at least the ones we've documented:
2013:
2011:
2008:
As you know, Google has actually changed their logos and signage on their buildings for the month as well.
Forum discussion at Google+.