It's the 40th Anniversery of the Kent State shootings. It was always a popular subject in my house growing up. First because my family was quite liberal, two because it was in Ohio where I am from, not far from Cleveland, and three, because my mother was pregnant with me at the time. She always said it was the first time she felt me kick was when she heard the news.

Here is a link to a wikipedia news article.
http://en.wikipedia.org/wiki/Kent_State_shootings