Talk about impact - this was Google's way to draw attention to a conservation effort called Earth Hour. The idea was for everyone to turn out their lights for an hour to raise awareness for environmental efficiency. And of course, it was effective.
Stations can do the same things, with their familiar logos coupled with the power of their websites. WRIF (and the original ABC-FM Rock stations) frequently used their ubiquitous oval logo shape to tie into all sorts of events, celebrations, and connections with Rock bands, sports teams, and whatever was happening in the area. Many stations wrapped their logos in the Stars and Stripes to make a patriotic statement during the Persian Gulf War, and after 9/11.
And today, our websites can perform the same function - in a real time, current way. Google has used its powerful logo and its much-visited website to make their brand more than just a search engine. It's a great way to send a message whenever they like. And because they are a trusted destination, these statements get noticed.