Carlos Miller, author of the Photography is Not a Crime blog, was attacked by a Miami-Dade Metrorail security guard. The guard stole Miller’s video camera (though it was eventually returned). When Miller began filming with his iPhone, the guard began pushing him while attempting to steal the phone. Eventually, the guard struck Miller and he struck back.
Miller managed to get video (captured by his iPhone) of part of the incident up on YouTube.
For the full story, see Miller’s blog. The entire incident was captured by a news crew and will eventually be on HDNet TV World Report.