This idea is just an extension or a particularization of the location based rss feed (like a location based digg).
The idea is quite simple. You can associate existing web pages to points on a Google map. For attach the wikipedia page of the Guggenheim museum of Bilbao to the location of the museum in the map. When a mobile users is in the museum, he will have this wiki on his RSS feed on the screen of his mobile phone.
You can also localize online newspaper articles, blog posts, twitter pots.
The main problem of this approach is that a most content of the web is aimed to be topic specific but geographically universal.
Where would you localize Martin Varsawsky's blog? Even you may be able to localize some posts. This blog about entrepreneurship is intended for everybody no matter where.
