Long story short; a known criminal waved a replica gun at police officers, and the police officers, not knowing it was a replica (how could they, really?) shot him. His family staged a peaceful protest outside the station as the police were being vague about it all, then it got hijacked by rioters, then the idea that looting shops and stuff would be fun spread and now everyone is doing it for...some reason. I'm not sure what, but I'm guessing it has something to do with the fact that they want an HD TV and don't want to pay for it and hey look, that electronics shop has just had its window smashed, let's go there!
So, yeah, that's what's going down in London and the rest of the UK at the moment (why the hell is there rioting in Birmingham and Liverpool?!)