There’s no better known or infamous teachers union boss — or leader among America’s public sector unions — than Randi Weingarten, the cunning, charming, and oft-quotable president of the American Federation of Teachers. A frequent guest on shows such as The Colbert Report (on which she declared that teachers in Wisconsin, Ohio, and Indiana skipping work to oppose efforts to abolish collective bargaining rules wanted to "make a difference in the lives of kids"), she is as comfortable on the talk show circuit — and playing the villainess in popular films such as Al Gore pal Davis Guggenheim’s Waiting for ‘Superman’ — as she is at protest rallies. Unlike Dennis Van Roekel, the low-profile (and low-charisma) president of the much larger National Education Association, the quick-quipping Weingarten is more than willing to go toe-to-toe with big-name reformers such as Microsoft mogul Bill Gates and the notoriously combative Michelle Rhee, with whom she tangled for years, especially…