Joe's all over the place today. On "Nightline" last night, he told Terry Moran:

"To be honest with you, that infuriates me," plumber Joe Wurzelbacher told Nightline's Terry Moran. "It's not right for someone to decide you made too much---that you've done too good and now we're going to take some of it back." "That's just completely wrong," he added.

He went on to rail against progressive taxation further:

"I don't like it," said Wurzelbacher. "You know, me or -- you know, Bill Gates, I don't care who you are. If you worked for it, if it was your idea, and you implemented it, it's not right for someone to decide you made too much."

Joe Biden kept it classy by questioning the motives and honesty of Joe Wurzelbacher:

Our friends on the Left show their respect for the working men who happen to ask them inconvenient questions by
putting up "crack" pictures,
alleging he's a McCain plant, and
devoting multiple discussion threads to tearing him down on DU.
Ben Smith is looking into whether Joe is registered to vote. God speed, Joe. The national election arena can be a rough one to be thrown into. Just ask Sarah Palin. But all the hassle, background checking, and even abuse is in a politician's job description, not a plumber's.
Update:
He is registered, as a Republican:

Linda Howe, executive director of the Lucas County Board of Elections, said a Samuel Joseph Worzelbacher, whose address and age match Joe the Plumber's, registered in Lucas County on Sept. 10, 1992. He voted in his first primary on March 4, 2008, registering as a Republican.

All those on the Left who have been touting Obama's ability to pull Republican voters will now suddenly decide that being a Republican invalidates Joe's criticism entirely. Joe's feeling the spotlight's heat:

"There's a lot more important issues than me, and I'm starting to feel a little uncomfortable with it," he said. "Everyone's more worried about what Joe the Plumber has to say than what Obama or McCain has to say."