Jay Leno's guest list for his first two weeks back on The Tonight Show features A-list talent the likes of whom never appeared on the show during the brief time that it was hosted by Conan O'Brien. (Some commentators have suggested that Leno had first dibs on top talent for his 10 00 p.m. show and that O'Brien ended up with the leftovers.) Among those guesting beginning next Monday are former Alaska Gov. Sarah Palin; American Idol judge Simon Cowell; Winter Olympics winners Lindsey Vonn, Apolo Ohno and Shaun White; the cast of Jersey Shore; and Oscar-nominated actor Christoph Waltz.