John McCain's 2008 Sell-Out Express Tour continues around the country. Last night's show was in New York, where the politician who once seemed like the genuine article continued to look like an article in the National Enquirer.

McCain appeared on Letterman, where he "announced" his candidacy. "I am announcing that I will be a candidate for president of the United States," the senator told the talk show host, in what can only be described as the least interesting piece of political news since Tom Vilsack dropped out the race (I know what you're thinking, but it's true -- Tom Vilsack was running for president. But his candidacy never quite generated the buzz of say, Elizabeth Dole).

After shocking the world with his faux announcement, McCain announced he'd be announcing again in April. Wow. Quite an exclusive. Look, I wasn't born yesterday (though if I had been, this would be a terribly impressive blog from a one day old baby). I know candidates form exploratory committees -- that's announcement #1. Then they leak word that they're likely to toss their hair gel into the ring -- that's announcement #2. Then they appear on Letterman or "The Daily Show," something hip the young people watch -- that's announcement #3. Then they file paperwork with the FEC -- that's announcement #4. Finally, they give a speech and make it "formal" -- that's announcement #5. And -- of course -- it works. CNN, MSNBC and Fox all covered the Letterman appearance as if actual news had been made.

But McCain's participation in this media charade is a metaphor for who he is -- and a sad reminder of who he once was. He seemed so different in 2000, didn't he? Challenging not only George W. Bush's money machine, but the entire backward orthodoxy of the Republican party. He called Jerry Falwell and Pat Robertson agents of intolerance. Then he spoke at Falwell's Liberty University commencement.

It all began in 2004 when McCain made a deal with the devil to get access to the Bush financial network and started accumulating frequent flyer miles on Air Force One, actively campaigning for Bush's reelection and spurning John Kerry. It has continued right through the Fallwell/Robertson fiasco up to McCain's cheerleading for the president's escalation in Iraq.

Sure, in 2000 he benefitted from fawning press coverage (just try to find an article from the campaign where he wasn't referred to as "the maverick Arizona senator"). But they fawned for a reason. He was a straight shooter. He did tell it like it is. He was (insert cliche here). And then, after nearly four years of useful criticism, that McCain was gone, another politician willing to do or say anything to become president.

That's why Wednesday night's Letterman appearance is worth disparaging. Because there was John McCain, once a rare American phenomenon, the authentic politician, suddenly taking his cues from the pages of guys like Sam Brownback.

How sad.