Seems like a good, and necessary, effort to me. Problem is, of course, that anyone who believes these stories will probably not trust anything coming from Obama's campaign at all.
As researching urban legends is sort of a hobby of mine, I visit snopes.com very frequently and I must say there's been far, far more stories aiming to discredit the Democratic nominees debunked there during the campaigns. I've been wondering a bit why exactly that is. Perhaps it's due to the fact that the nominees were a woman and a black man (whose father was once a Muslim), making many people uncomfortable but unable to publicly express it due to social norms (urban legends tend to serve as a vent for such feelings). Or the lengthy battle between the nominees sparked the rumors. Or Snopes simple has some kind of political bias and spends more time debunking rumors about the Democratic nominees.
Either way, with all the false information being spread for propaganda purposes, perhaps every presidential candidate should consider establishing a similar site. There certainly are some things McCain could straighten out what way - he may have a temper and a knack for making offensive (although sometimes admittedly hilarious) jokes, but some of the things he is claimed to have said could use some critical examination.
