Guatemalan lawyer Rodrigo Rosenberg wrote a letter and recorded a video on May 9 saying if he was murdered while uncovering bank corruption that President Alvara Colom of Guatemala would be personally responsible and complicit.
The next day Rosenberg was murdered while rising a bicycle. Guatemala erupted into protests and have been using Twitter and Ustream.tv to spread the news and organize. One twitterer, Jean Anfer, was arrested and sentenced in one day for a 140 character twitter message about the bank urging people to withdraw money to force it to collapse.
Xeni Jardin at Boing Boing is also covering this closely. Start here.