Lights at Bing Homepage will go off on 27th in honor of Earth Hour. The bing blog said -
“On Saturday, March 27th from 8:30pm to 9:30pm local time, the World Wildlife Fund invites you to join people from 3,100 cities in 121 countries on all 7 continents in participating in Earth Hour, where people across the world can demonstrate their concern about global climate change with the simplest of gestures: turning off all non-essential lights and electronics.
While a darker version of our page doesn’t save any energy over the regular version, we wanted to do our part to help spread the word. So in honor of Earth Hour, the Bing homepage image will go dark at 8:30pm Eastern Daylight Time and stay dark until 9:30pm Pacific Daylight Time.”
To find out more about what you can do to support Earth Hour, see http://www.myearthhour.org/community.
EDIT : Check out the animation of the Bing Home page- The regular Bing HomePage and the HomePage during EarthHour