"It's the passivity of the blog operator that is the source of the immunity," Kirsch adds. "If you take something and you feature it, you boldface it, you take it out of the general run of postings and highlight it, then you're approaching a line, and you may have crossed the line."

Some questions about just how far Section 230 protection extends may be answered later this month, when the Ninth Circuit Court of Appeals rules on the case of Fair Housing Council of San Fernando Valley v. Roommate.com.

"It's going to be the first time a full federal appellate court has looked at the difference between content that's created by a third party and content that's either invited by or mixed with content created by the site itself," says Burke. "I don't think there's any website today that isn't or shouldn't be closely following what happens with that decision."

But that still leaves the matter of conscience. Jeff Jarvis, a blogger who has written extensively about the ethics and economics of Web publishing, says it's not as simple as saying that egregious comments should be deleted.

"I don't think there is a blanket rule," Jarvis says. "Part of the problem is that there is a falling bar on the definition of offensiveness. We live in an age of offense and political correctness when someone can be offended by anything said and someone can insist that speech should be silenced. There's danger there. In a free democracy and an open market, we must value open discussion and the exchange of views and ideas. So who's to say what goes too far?"

"There's nothing wrong with setting ground rules and making participants stick to them," agrees Andy Schotz, chairman of the Society of Professional Journalists ethics committee. "Some people, though, don't mind a free-for-all atmosphere. Readers can adjust their opinion of the credibility of the site accordingly."

Clearly, the Huffington Post believes it has a responsibility to filter out the worst of the worst. After O'Reilly's criticism, the site has quietly encouraged its moderators to be extra careful not to post comments that violate its guidelines.

"There's a zero-tolerance policy when it comes to abusive comments," says a spokesman. "For the most part, our conversations are completely civil, but we have more than 400,000 comments each month."

Then there's Gawker. Although its comment forums can get as rowdy as Deadwood's Gem Saloon, Gawker seldom, if ever, deletes individual remarks.

Explains Denton, "I look at Gawker comments as a party. We don't take responsibility or credit for individual comments, but we have the right to invite or disinvite guests and throw the best party we can.

"Just as a host isn't responsible for the vomit in the corner," Denton adds, "we don't take responsibility for individual comments."