Many people have been arrested for recording public arrests, and many others have had their cameras confiscated, and that's here in American where we have the First Amendment. At Gigaom, Matthew Ingram takes a look at this problem and concludes that the freedom of the press applies to everyone, even bloggers:

University of Pennsylvania law professor Seth Kreimer, who has written a research paper about the right of citizens to record public events under the First Amendment, told Reason magazine that rulings by three separate federal appeals courts have upheld that right. And one recent appeals court decision specifically referred to the fact that the ability to take photos, video and audio recordings with mobile devices has effectively made everyone a journalist — in practice, if not in name — and therefore deserving of protection.

Ingram's article cites to another well-written article, this one by Rodney Balko, titled, "The War on Cameras." Balko's article discusses the right to privacy of police. Here's an excerpt:

University of Pennsylvania law professor Seth Kreimer, author of a 2010 paper in the Pennsylvania Law Review about the right to record, says such legal vagueness is a problem. Citing decisions by three federal appeals courts, Kreimer says the First Amendment includes the right to record public events. “The First Amendment doesn’t allow for unbridled discretion” by police, he says, “and it’s particularly concerned with clear rules when free speech rights are at stake. Even if there is a privacy interest here, people have to know when they’re going to be subject to prosecution.”

Here's the article by Seth Kreimer; it's titled: "Pervasive Image Capture and the First Amendment: Memory, Discourse, and the Right to Record."