Jak Bouman has posted about the Monkey Murder Mystery which started on Oct 4th:
From October 4th, 2007 a real street game, the Monkey Murder Mystery, will start in four Dutch cities. The Monkey Murder Mystery is a local interactive reality game, which gets gamers away from their computer. The gamers will hunt or be hunted, not with a water or paint pistol, but with a camera equipped mobile.
Check it out: http://www.monkeymurder.com/