I think about it as a more awesome faction event system:
You met a NPC in your way to some dark forrest.He managed to trap another NPC on a magic trap spell, but running away from there he left the ring that keeps on the spell, he ask you to get it for him, he's tired and wounded so he can't go himself.
At the same time another player mets the imprisoned NPC in the forrest, he says another NPC trap him there, but that a ring is the device that keeps the spell on and he "feels it" in some place in the forrest.
So both make an oath to each NPC, they now are playing against other without knowing it. They may found each other in the forrest, but they don't know what are really doing each other there, so what will happen when they realize they are in different faction? who will realize first so he can set a trap to the other player? they may even never realize they were in the same forrest, anaway, they may been allies in the past....
The possiblities are endless, it could be even better if From would add new events every few weeks or so.