INTERESTING: Someone at the meetup (not me! who?) noticed that our group showed up at 3PM and had name tag stickers. Then lots more people showed up for the SENS thing proper. All the LWers were more familiar with each other and were marked, so there was a visible "faction effect" as we stuck with each other the whole night. If it had been on purpose but secret, it would have been a frighteningly Machiavellian way to encourage a sense of solidarity among the LWers... if it had been on purpose with "informed consent" it might have been a great way for us to consciously build group cohesion :-P