Scrutiny reports '203 non-authoritative information'. W3C elaborates on this a little bit:
Partial Information 203
When received in the response to a GET command, this indicates that the returned metainformation is not a definitive set of the object from a server with a copy of the object, but is from a private overlaid web. This may include annotation information about the object, for example.
So this means that a third-party is providing the information you see. Presumably this is no different from something many of us do - making some space available on the page and allowing Google or another third party to populate it with advertising. (And indeed the page you get at the domain in question here is the kind of thing you'd expect from clicking on an ad).
What's interesting here is that you can visit a domain and see a page not controlled by the owner of that domain. I guess a less responsible owner wouldn't have the server give this response code, but this seems to me like information I'd really like to know while I'm browsing. Should your browser alert you to this?