As for your first statement, that these groups aren’t new structures “but simply new types of interest groups that now have a surprisingly loud voice within existing political structures,” at what point does a change in degree become a change in kind? We’ve always had a large number of political groups/audiences/interests clamoring for attention, but new media create the opportunity for an increase that’s at least one order of magnitude.

At some point, to extend an earlier metaphor, we may see a phase change — just as water goes from liquid to gas at the boiling point, this explosion of new niche audiences may create a political environment that is so changed that it’s clearly a new structure. I’m not willing to say that we’re there yet, but it sure is getting hot in here.

–cpd

However, I don’t what you have described as alternative politicial structures, but simply new types of interest groups that now have a surprisingly loud voice within existing political structures. MoveOn is powerful within the Democratic Party because politicians know it can move butts and raise bucks. That’s true of all the groups that you mentioned above. The fact that these organizations are exercising leadership outside of the party machine power structure shouldn’t be surprising, it should be expected once they are able to achieve critical mass. Personally, I think it is remarkable that critical mass can be achieved relatively quickly.

If you really want to know my opinion, I would say that there is practically an inverse relationship between the celerity of achieving critical mass and the degree to which your rhetoric jibes with existing party structures. In other words, the more MoveOn pushes counter-party leadership tactics, the stronger their base. The more Rush goes after party leadership and criticizes candidates for being too ‘squish’, the more likely his base is to continue to look to him for leadership.