Besides pointing out that the Internet is anything but neutral and that net neutrality regulation would be a boon for lawyers and bureaucrats, as Bret noted, Peter Huber also points to a favorite theme of mine, i.e., net neutrality regulation would prohibit network operators from from providing free or reduced-price broadband connections supported by advertising (see, e.g., this, this, this and this).

Not long ago Google successfully bid to deploy a municipal Wi-Fi service for the city of San Francisco. As one part of that proposal, it promised to offer a free tier of wireless access to all. Free means paid for by advertisers, whose pitches will be the first thing you see whenever you log on to San Francisco's Google-neutral network. The whole free broadcast network--radio and television--was built this way. But the net neutrality law would outlaw any comparable arrangement on the Net. It would be verboten, that is, for content providers to share the cost of running digital connections to the customers they most want to reach.

See: "The Inegalitarian Web," by Peter Huber, Forbes, Feb. 12, 2007