The Mama Grizzly is coming out of hibernation. This weekend, Sarah Palin is launching her "One Nation" bus tour, visiting historical sites across the country. Palin will start on Memorial Day at the Rolling Thunder weekend motorcycle rally that starts at the Pentagon. Where it will end has yet to be announced. But given Palin's other recent move—the announcement of a feature-length film on her tenure as governor—it looks as if her ultimate destination may be the White House. Whatever Mitt Romney had on his plate for Memorial Day, he'd better make room. If we assume—for the purposes of page...