Location based games

Paul Baron has made this splendid list over existing location based games. These games usually require a mobile phone and a GPS, and takes place in an outdoor area, preferably a city.

I would like to see some research be done on this subject. Is there for instance any inventive game play going on here, or is it more like a new arena for already existing (live) games? What I find most intriguing is the question of what ontological status a game with such blurred boundaries will have. I accidentally found a quote from Baudrillard, in Frank Schaaps book about roleplaying MUDs that speaks of another "collapse" in the boundaries between reality and virtuality:

Disneyland is there to conceal the fact that it is the "real" country, all of "real" America, which is Disneyland...Disneyland is presented as imaginary in order to make us believe that the rest is real, when in fact all of Los Angeles and the America surrounding it are no longer real, but of the order of the hyperreal and of simulation.
Baudrillard (1983)

This might be a bit too subversive for most people, but in the case of these Location based games we can actually see the "real" America become more virtual than what is normally agreed on.