The FCC made a ruling on Comcast's network management (or P2P traffic interference). There are 2 blogs that give an excellent view of the ruling - one is from OpenID and the other from Prof. Susan Crawford.
I wonder why they just don't use the Common Carriage definition. If cable is a Common Carrier like telcos then stuff like DPI and traffic interference are a no-no. What? You mean Embarq and others are infringing on Common Carriage with something like NebuAd and Sandvine? No. Couldn't be. Not with the FCC around protecting the consumer and stuff. Oh, wait. ILEC's have a hall pass. I forgot.