The post generated lots of comments, and I'm very grateful to all those who contributed via public comments or private emails and tweets. That evening as I sat pondering what to do, all the pieces clicked into place and I had the answer: a little social engineering.
The big dilemma I had was how to alter user behavior so that people stopped trying to develop the Small Worlds wiki into a social network and simply entered their details before going off to join existing networks on other sites. In addition, I wanted an easier way to be able to get at the user data stored on WetPaint. The answer turned out to be a fairly simple site redesign, moving the user data onto more prominent wiki pages.
This wouldn't have happened without the discussion which took place here yesterday. This sort of collective problem solving is the reason I blog openly about my work. I heart SOTI readers :-)