Merging games with reality

Today we learned about pervasive games these are games in which take place within the real world
for example Killer where players "kill" each other with fake weapons  this adds a whole lot on to what we think about games and maybe a new way to promote games and businesses.
You could use this way to promote games and products such as books and films. For example if you are releasing a mystery game or book you can set it up so that you have your own investigation where  people can solve puzzles and find clues.