According to
ABC News, a bill has been introduced in the House of Representitives (as the "Deleting Online Predators Act of 2006," H.R. 5319) that would ban any website that allowed minors to interact. According to their definition, this would include Wikipedia, ChiefDelphi, any other wiki or BBS, any blog, any web host, etc. etc. Also under this bill, any IM or chat would be banned.
Granted, this is still an early form. However, I'm posting this here so that everyone knows to watch for this bill getting shot down, and to write their congressman if it doesn't.