It's not yet clear who perpetrated the hoax announcing that the Chamber of Commerce had changed its position on climate change. (It hasn't, and remains opposed to serious efforts to deal with the problem.)

But some evidence points to the Yes Men, a group of activists known for similar stunts.

An email address attached to the domain name registration for the website hosting the fake press release has also been identified in online postings as being tied to a November 2008 hoax which the Yes Men played a role in, involving handing out fake copies of the New York Times announcing falsely that the Iraq War had ended.

The Chamber told TPMmuckraker it doesn't know who was behind the hoax, and is looking into it.

Neither of the Yes Men's two principals, Jacques Servin and Igor Vamos, responded immediately to requests for comment from TPMmuckraker.

Late Update: A spokeswoman for Avaaz, an international activist group, told TPMmuckraker that the Yes Men were indeed behind the stunt, but did not elaborate. She gave us the number for "Erica Avidus", the Chamber spokeswoman who appears not to exist. Earlier, an Avaaz administrative staffer had told TPMmuckraker that Avaaz's "Action Factor" had been behind the stunt. So right now, we're putting our money on a joint project of Avaaz and the Yes Men. But we still don't know for sure.