It's an international campaign.  Here's reference to <a href="http://chicagoist.com/2009/10/20/atheist_billboard_downtown_stirring.php" rel="nofollow">a Chicago campaign</a> stating "Are You Good Without God? Millions Are."  It's caused quite a stir, and many billboards and bus ads have been vandalized by people who seem to disagree with sharing the thought that it's valid to be a good person without God in your life.

See photos from <a href="http://www.flickr.com/photos/charleskrause/3345472825/" rel="nofollow">a Toronto bus</a> or from <a href="http://www.khq.com/global/story.asp?s=11355159" rel="nofollow">Moscow, ID</a>.  British Christians have put out their own ads and <a href="http://www.christianpost.com/article/20090216/christian-party-offices-vandalized-after-launch-of-bus-ads/index.html" rel="nofollow">felt some consequences</a>.  Of course, some people would find that the pro-religion reaction to the billboards to be somewhat <a href="http://cectic.com/comics/159.png" rel="nofollow">hypocritical</a>.  

I don't consider myself an atheist, but the overwhelming culture in the US is one of Christianity.  This isn't the time or place to argue the appropriateness of that, but I would suggest that the only reason this is getting so much attention from news outlets is that atheism is still seen as an invalid or crazy belief system.  Note the difference in tone from the atheist ads and religious sayings and messages that we see every day.  The atheists are just suggesting that something else is out there, a questioning of the status quo, whereas the religious messages tend toward the obvious "truth" of their statements.  And from that we see vandalism and news reports about how atheists are really "shaking things up".