the value is who you are doing it with....
For sometime now I have been advocating that there is more value in knowing who you are doing stuff with than you on your own. Orange at Glastonbury have done something special. With a very high res photo of the crowd you can confirm you were really there and start to link up with who else was with you. This is also a foundation of digital reputation, I said I was there and now can prove it, using "open technology" Yes the ticket sellers know who you are and could sell you next years concert and other interesting gigs, but now the world knows who you are and what you like ( assuming you want to tag yourself in) eHarmony wants to match by preference, this allows you to find that match after the event. http://glastonbury.orange.co.uk/glastotag/
It also looks like some where not there - but are tagging themselves into the photo in odd places and dual tagging. Cool just to have the "badge"
Not so great if you happened to tread on someone's toes, who is now trying to find you.... but so what.