While Arrington aggressively tried to position FriendFeed as encouraging mob mentality, Bret touched on an interesting point that helped explain the scenario. Essentially, most conversations are decentralized across social networks. But on FriendFeed, conversations are centralized. While not threaded, all of the site's users have the ability to make comments on any open public conversation - meaning those people with extremely popular accounts can have a high amount of comments, and as comments come in, these items are pushed to the top, making them visible again.
Bret said that new tweaks are going to soon come available on FriendFeed that would enable users to stop comments on particular entries, or on the person's entire feed itself. This means that if Arrington were to re-enable his account, as he said he would do today, he could opt to mute threads that got out of control, or simply post his feed and make it unavailable for interaction. Interestingly, Bret said that the conversations on those accounts that had either a small amount of followers or a large amount were of the lowest quality.
Scoble, the most-popular person on FriendFeed, who had trouble getting his audio into the conference from London, actually agreed with some of Mike's assertions, saying "there is a mob mentality, and we caused it". He added. "We brought a huge crowd... and people are going to get in the bleacher seats and throw rotten tomatoes every once in a while."
Bret did not give a timeline for the new features, but if FriendFeed's speed of feature improvements thus far is any indication, they won't be too far away.
You can also see a timeline of this panel here: Mike Arrington, Bret Taylor and Robert Scoble starting the "Online Mobs" discussion.