I also wanted to add that social media can give you a false idea of how well known something is. It may be 2011 but mainstream media still trumps social media. For example, whenever a case is getting lots of activity, there are always people who insist that the entire country knows about this, and if you don't, you live under a rock. The reason for that thinking is that the Internet allows you to spend as much time researching a case as you want. You can read news articles, blogs, comments, forum posts, etc and get the notation that the entire country is talking about a case. Unlike 15 years ago, when the media completely determined when you heard about a case, nowadays, you can hear about a case as much as you choose.
Also, let's remember that the Internet is extremely vast. There may be six billion people surfing the net, but there are also billions of websites. Just because six billion people can read your blog about a missing child doesn't mean that any more than a few dozen actually are. When the Lindbergh baby case happened 75 years ago, its only media source was the newspaper, but I can guarantee that the entire country knew what had happened to Charles Jr. Every newspaper in America put that on the front page, and since the newspaper was the only place to get the news, everyone heard about him. It may have been much more difficult for a missing child to make the news back then, but I bet the ones who did were more well known by a larger percentage of the US population than the popular cases today.
BTW, this post doesn't really apply to the Anthony case as it's a very popular case in the mainstream, but more to cases like Haleigh Cummings, Kyron Horman, Lauren Spierer, Holly Bobo, etc who I don't think are as well known in the mainstream as the Internet would lead you to believe.
