I'm a long time member of Nexopia and I can say we are not really excited by tynt. If you don't want to take my word for it you can read the Nexopia forums for Graffiti.
20000 graffitis done by 1.3M members is pretty bad. We're not "crazy kids," we use Nexopia a lot and don't see the point of graffiti, it is really slow and kind of a joke.
Everyone knows Nexopia does over a billion page views a month. this makes 20000 tynt pages meaningless. From what I can tell, no one is using the feature. It was like a few people tried it out as a novelty (like the Christmas Elf thing last year) and never used it again. As a member of Nexopia, I don't like other companies trying to use us for their marketing propaganda.
I haven't seen anyone using the graffiti tool at all. We keep it real with real graffiti, 12ozProphet Graffiti Forum is where its at for REAL graffiti for nexopia.