The almost non-partisan FactCheck.org looked at Obama's and Joe's claims about taxes and reached some reasonable but incomplete conclusions:

At their encounter, Wurzelbacher told Obama that "I'm getting ready to buy a company that makes 250 to 280 thousand dollars a year," before asking whether or not Obama would raise his taxes.

If the company is actually that profitable, and depending on how the business is organized legally, Obama's plan would indeed raise his federal income taxes, and Obama conceded as much during the exchange. As we've written before, small businesses commonly are organized in such a way that their owners file business taxes as individuals. So if Joe's plumbing business earns more than $200,000 per year (or $250,000 if Joe is married and files tax returns jointly) then his taxes would indeed be higher under Obama's plan than under McCain's.

It's worth noting that while Wurzelbacher told Fox News' Neil Cavuto that he lives "in a simple, middle class home" and portrayed himself as an ordinary working guy, Wurzelbacher's $250,000 to $280,000 is a bit higher than "ordinary." In 2007, the last year for which the Census Bureau has figures, the median income for a family in Toledo, Ohio, was $43,553.

McCain: Now, my old buddy, Joe, Joe the plumber, is out there. Now, Joe, Sen. Obama's plan, if you're a small business and . . .  you've got employees, and you've got kids, if you don't get - adopt the health care plan that Sen. Obama mandates, he's going to fine you . . . I don't think that Joe right now wants to pay a fine when he is seeing such difficult times in America's economy.

McCain raised a similar charge at the last debate. It's still false. Obama's plan, which is posted on his Web site, specifically says, "Small businesses will be exempt from this requirement."

Obama hasn't defined exactly what he means by "small" but he seems to think Joe would qualify; he repeatedly referred to Joe's "small business" during their exchange.

Obama's health plan does mandate that children have health coverage. If Joe doesn't provide insurance for his kids, he would face some unspecified penalty.