Okay, the changes to the nameservers have taken effect. I can no longer see the offending site.
I still have not heard anything from Dreamhost, and it has been almost 24 hours since I put in my support request. Is this typical?
I DID, however, receive an email from the guy that put up the site. He says that it appears on his control panel, too, and that he thought he had purchased it (along with the .net version) several months ago.
Of course, this is impossible, since I have always kept my renewals up to date.
If it does indeed show up on his control panel, that means that Dreamhost is taking money from two different people for the same domain name!!! This would obviously be a VERY unethical and shady business practive on their part.
I will wait to hear from them. If any one else has any advice/experiences to share, I would appreciate it.