Right now, merely steps away from our humble D.C. bureau, First Daughter Jenna Bush is signing copies of her new book, Ana’s Story, at our local Borders. Except for an extra helping of Young Republicans milling around in New Paperbacks, you wouldn’t even know she was in there. The turnout is modest at best, a sign, perhaps, that book publishing is a brutal business, even with White House connections. Still, Bush’s book ranks a very respectable 729 on Amazon…