It looks like he is hosted at
www.webmasters.com
Webmasters.com are hosted by Sago networks,
www.sagonet.com
The domain cloaking through GoDaddy is not against ICann regulations. A lot of people do that now.
Other than that, good luck finding out who he is unless he is doing something you can subpeona Godaddy, Webmasters.com or Sago Networks for.
You could always set him up to find out more about him. I don't think it would be that hard to do. Hell, just e-mail him for advertising rates, check his IP when he replies and go from there.
What happened? Did he steal your content?