Sitting alongside my thoughts on check-in based location services, I've also been looking at another angle for using GPS and an internet connection. Drop yourself into a mystery location and ask yourself how you would find out things like: what has happened around you, what that castle is, and which exhibits are in the museum on the horizon. You could ask the locals or look up a tourist guide...
...or you could use your smartphone. It knows exactly where you are, and with that information it should be able to go online and find all that out for you. That's what Locago does.