"A frequent commentor on Democratic Underground, Castagna was also a regular on the right-wing message board Free Republic under the nom de rant, Marc Costanzo."
That's not what it says at that link now. (Did someone edit it?) When I go to the article that sentence reads:
"More about Castagna came out via a commentor on Democratic Underground, who pointed out Castagna was also a regular on the right-wing message board Free Republic under the nom de rant, Marc Costanzo."
The DUmmies pressured Radar to edit the story. They have a thread about it.
I noticed that too. Someone edited the source, as it no longer says this person was also at DUer.