The nature of this site will attract some very litigious people and organisations:
What happens when they sue, will Jeff and Joel drop us like a hot potato? Or will the site be censored?
The site is hosted in the United States, is it not? The US has strong free-speech protections, and just enacted a libel tourism law to prevent US courts from enforcing judgments obtained elsewhere (notably the UK).
As mentioned in that article there are other US laws that protect Jeff and Joel from lawsuits relating to content here, just as ISP's are protected from being sued over things posted by their customers. If such laws didn't exist, things like Twitter could not exist. Consider the Courtney Love lawsuit just settled, note that Twitter itself was not a party to the suit.
However, I AM NOT A LAWYER.