Photosynth Demo
If you have a few minutes, you should check out what’s in store for linking photos together. Note that this isn’t just limited to photos. Newspapers, books, and probably just about anything you can think of in the future may be linked together, on a world wide scale.
It does make me wonder though, how copyrighted/digital rights material will be protected from being linked with this. With stories like the lady who’s upset with Google Streets with having a picture of her cat on the internet and wants it removed. I imagine we’ll eventually be hearing about how people thought their personal photos weren’t available to anyone surfing the internet when they used sites like Flickr, Smugmug, etc. 
You can read up more on Photosynth at Microsoft Labs