I think mobile apps which do this are coming, and the iPhone SDK hasn't been available long enough for really spectacular stuff to have come out. It takes a whi

I think mobile apps which do this are coming, and the iPhone SDK hasn't been available long enough for really spectacular stuff to have come out. It takes a while for a neat, massively-socially-networked (how's that for a neologism) mobile game to gestate. Here's a freebie idea for someone adventurous: a few years ago, I read about some online game, where players would sign up for some kind of a spy, murder, and conspiracy thriller. They would then periodically get emails, phone calls, faxes, and letters, to which they should react in the real world, and which advanced the plot. I don't think this was particularly multiplayer, in that I don't think that players interacted with one another. I think using the location awareness of an iPhone could make a thriller game like this incredibly exciting and immersive. Imagine a beeping device guiding you up the stairs in a building, telling you where to find the next clue? Telling you to quickly contact another investigator, because she found something and needs to share? Pitching teams one against another to follow a trail of clues in a race to find a hidden object somewhere in the city where they play? Implementing this would, without a doubt, be hard. Dealing with the liability issues alone could possibly sink this idea (e.g., how can you safely put random people in touch with one another, how can you ensure the safety of a particular building or other locale, and so on). In addition, it probably would require a fair amount of coordination and manual work by the organizers, so the game would have to cost a pretty penny to play. It would also have to have settings like "only play the game between 7 and 8:30 in the evening," which would of course be an even bigger nightmare of logistics. Of course, if someone figures all this out, it could become a huge hit.