this is no game. it is big stuff, close to the localisation trend. very linked to mobile world obviously. google/twitter/facebook are all going in the localisation in order to get data closer to the user. They are more likely to be relevant to them.
possible usage scenarios
"where are my friends"
"i like this personn, oh this personn is going there, oh i dunno this place, maybe i will like this place"
"oh you went to this bar ? i like it too. ask bob the barman to give you one drink on the house, i know him"
obviously once the arch is setup, it is possible to push local store ads on this. It think local-store ads on the internet will be huge, once the arch is setup, so not soon, but in a few years.
The deployment of local ads is slow, because you need to get local stores to actually advertize... and they are not used to it. This is my understanding of it at least. aka "the market is not yet ready".