If they have it listed or want you to find it, then yah. Otherwise you probably should'nt be contacting them if they didn't make it easily to find. But if you are persistant I would: Check there profile, find out the sites they list as there homepage and perhaps the sites in ther sig line. Go to those sites and see if a contact email is listed.. If so it might be their email, if it is the same email on all the sites, then it probably it thiers. Or if you can't find an email listed then look up one of there sites in the WhoIs registry and see what email is listed as the contact email. I like to use http://www.DomainTools.com. Check all the sites in there siggy, if they don't have private registration and all the sites are owned by the same person than it's probably their email address. That's about as far as I would go I think.
It would kinda be hard but you can search for it and find it with no worries. I think that is why I like myspace better.