You've seen them on television, you've read about them in magazines, you've heard from them on the radio -- and now Al and Tipper Gore spill their guts (or, at the very least, flog their books) in The Reliable Source. Last week in New York -- sandwiched on their schedule between Katie Couric and David Letterman -- we finally redeemed our long-promised lunch with the ex-veep and his wife. They're in the midst of a media juggernaut to tout two joint publishing ventures: "Joined at the Heart," an anecdotal book on the modern American family, and "The Spirit of Family,"...