http://www.politico.com/news/stories/0612/77502.html Heh! Sen. Tom Daschle has an article from yesterday about the meme that "if the health care bill stands, Congress can make you buy broccoli". He of course goes on about how that's silly and we really need this law...
But then he says: "Yes, Congress could require Americans to purchase broccoli. But who would be stupid enough to even suggest it? Does anyone actually believe that we could find 60 votes in the Senate and 218 votes in the House to support it?"
So... he admits the central point that if the law stands, there's not really a meaningful limit to federal power. (Kagan basically admitted the same during her confirmation hearing, saying she'd defer to Congress.) But don't worry, a pure democracy would never do something evil like, oh, round up the ethnic Japanese into prison camps on general suspicion of "their kind", like FDR did.
This article by Sen. Tom Coburn goes on about the argument, citing the famous Wickard case among other things.