Brief mention in Washington Post Opinion (second page):
"While there have already been some attempts to create a true electronic currency, such as Bitcoin, these have had difficulty getting off the ground. It is not hard to see why. If it is possible to imagine one private electronic currency, then its possible to imagine several, and there would be no guarantee that other people would accept the particular electronic money you use."
http://www.washingtonpost.com/opinions/imagining-a-world-without-the-dollar/2011/04/26/AFjawKEF_story_1.html