The sites FactCheck.org, and PolitiFact have become for many pundits and the public as the goto place to debunk political myth. These sites examine the campaign spew to tell us what's true, what's a lie, and to point fingers at whose pants are on fire.
What people know about the candidates is strongly influenced by this stuff, true or not. Does Barack Obama support sex ed for kindergartners? Not really, but Fox News this morning repeated the claim. What's odd about that? Bill O'Reilly the night before, on Fox, fussed about the McCain folks using this misleading ad (and one by the Dems, just to be fair).
Pro campaign advisers know that what matters is getting the allegation out there in the public mind -- put the other guy on the defensive, sow doubt among the undecided, energize the base.
What people know becomes a function of the bits and pieces they've picked up from grazing on news and blogs and talking heads on TV and radio. This cobbled together picture often fits predispositions, and there are a lot of people with some doubt about Obama, a relatively new guy on the political block.
The GOP pros are exploiting this because they have a simple choice, the "Straight Talk Express," or winning. You'll see the Dems doing some of the same at Sarah Palin, though so far nowhere near what the other side has done so far.
Let a million factcheckers bloom.