Blocking Kazaa 2.0?

coder_ asks: "Has anyone had success blocking the latest versions of this annoying P2P application in a network-wide context? Previously, people have been told to block a specific port, etc, yet as expected, Kazaa has found an easy solution to this. Apparently, when a connection via default port is not available, Kazaa makes encrypted http requests through port 80, making it rather difficult to now block. If anyone has had success in doing so, I would love to hear from you."