Interesting post over at Rabett's: one Pat Michaels, who's done everything he could to cast doubt on the global warming consensus, now says with a few caveats that human-caused warming is real. Michaels does a convenient 180-degree turn for denialists. I think the real test now is whether he's another of the No Biggie Denialists, accepting some evidence while denying its seriousness. The real test for that position is whether it accepts the IPCC consensus. The impacts chapter of the latest assessment should be out shortly, and that will make the debate interesting.
I think Wikipedia needs an article on the history of denialism, following people who started skeptical and became convinced, and those who have just pirouetted to new positions, like Singer, to accept a subsection of the evidence while denying any need to do anything that they find politically inconvenient.