Every presidential candidate can use a sexy blonde movie star to liven up his or her campaign, appear at big money events and rally the entertainment community. Sen. Barack Obama's go-to Hollywood hottie is Scarlett Johansson, a starlet who trades frequent e-mails with the presumptive Democratic nominee, campaigns tirelessly on his behalf, hosts lucrative fundraisers and even appeared in that "Yes We Can" viral video that got 10 million views in its first week online. Drawn to his candidacy largely because of her anti-war views, she met Obama several times on the trail, talking to him one-on-one on many occasions....