The whois info is protected. Try domaintools.com , maybe you will be able to see who owned it before the privacy protection was enabled... but you won't know if that will be the current owner.
DomainsByProxy will not reveal the current owner(unless you have a court order)
Another thing that should be noted is, when using Godaddy's privacy protection, the email does not always pass through using the whois email address, Are you having trouble contacting the registrant? is this why your asking?