They are using the same method as Comcast, though they are more honest about it, as evidenced by this response from the company:

To ensure the best possible online experience for our customers, Cox actively manages network traffic through a variety of methods including traffic prioritization and protocol filtering. Cox does not prohibit the use of file-sharing services for uploads or downloads, or discriminate against any specific services in any way. To help our customers make the most out of their Internet experience, we take proactive measures to ensure that bandwidth intensive applications do not negatively impact their service. These network management practices are outlined in our subscriber agreement and Acceptable Use Policy.

Certainly, I can see how, during periods of high bandwidth, one might want to drop priority on bit-torrent or similar applications (full disclosure, I use bit-torrent), but this is basically blocking:

According to Topolski, Cox is in fact using traffic shaping to degrade p2p traffic. In analyzing a user log, he has concluded that Cox is using traffic shaping hardware to send forged TCP/IP packets with the RST (reset) flag set — with the goal of disrupting eDonkey traffic. He’s been unable to tell precisely what hardware Cox is using, but he notes that the technique being used is very similar to Comcast’s treatment of BitTorrent.

It raises two questions: what is it about cable companies that make them so inclined to bull this bull$#@!, and why are they going through a backdoor block, as opposed to simply lowering the priority of the packets on their own internal network.