A puzzling paradox related to Thinkbot, Globe Alive, and other IM-related directories: It's well documented that anonymity in virtual communities increases the likelihood of antisocial behaviour, so participants are at risk of abuse from others. Resolving antisocial behaviour would require a switch to a non-anonymous system, with the need for persistent digital identity and trust metrics/vouching/rating. However, switching to a non-anonymous system (using an open protocol such as Jabber) opens up participants to spam, which is equally unwanted.
It will be interesting to see how virtual communities such as Game Neverending cope with this, as they develop structured societies. By being within a contained environment, your identity within a multi-user game can build up reputation without causing you trouble by being linked to the outside world. Any spam or abuse will be contained within the game environment, so can be dealt with and punished by the rules which apply there. Still though, there's no way to stop an abuser coming back in again under a different name.
Voracious sci-fi readers: how do you deal with punishment in a world of shifting identity?