Concept 1 sounds great in principle but you will need to have A LOT of people with maemo products for this to work in reality. Its like the Zune 'social' concept - great in theory, but in reality it didnt reach tipping point.

Concept 2 sounds the most realistic and with a 'wow factor'. Id add that perhaps this could enhance the contacts application (if possible) so that all photos tagged to a contact show up in the contact profile.