I've seen more then a few posts talking about Aaron & Co.'s work to use photo geodata to map boundaries of locations, and overall, I think it is pretty interesting, if only as a proof on concept.

The main information these maps provide is an indication of Flickr's coverage of different geographic areas. It also shows the quality of their mapping of GPS data to Where-On-Earth ID's. So: cool.

I can think of a few other interesting correlations between geodata and other data that I would like to see, mostly around tags (as concepts) and location. For example, what would be the geographic dispersion of 'peace' or 'hate' or 'quiet'? Or, from an entirely different perspective, could I access my contact's photo's by location instead of timestream or tags?

I'm only now starting to pay attention to geo-stuff, but it is clear to me that, like libraries with their databases full of interesting structured metadata, Flickr has and is growing an interesting data set that they and others are just beginning to mine.