Exactly how the crowd came to be seen as a mob I'm not sure. Some of it seems to be sour grapes from whiners who haven't been able to get their own posts elevated to Digg's front page -- see Little Green Footballs' curiously prescient post, for example. It's human nature. If we like the result, it was the product of the "wisdom of crowds." If we hate the result, it was the result of "mob rule."
But I think something else was at work on Monday, and it's something the Web 2.0 theorists should show some respect for. Digg is, at the end of the day, a parlor game, but even the players of parlor games have the right to expect the game won't be rigged. The Digg audience reacted to the rigging of results on the site with a large and very effective protest. The protest's message to Digg management was that Digg users expected the site to be an honest broker.
I think the same principles are involved in both. Kevin Rose, founder of Digg, certainly recognized the seriousness of what he was faced with -- the loss of his site's credibility with its community. I wish Congress would recognize the same and do something about the DMCA.
Democracy is not neat. Even in the small things like the AACS protest it's a messy business, with no clear-cut rights and wrongs. Freedom gets really fuzzy at the edges where it runs into responsibility, but it's still worth fighting for. We live in a country that was founded in protest. We should know better than anybody that protest is often the wisdom of crowds.