Nearly four years after they clashed in a memorable TV interview, Sarah Palin and Katie Couric face off again - this time in a morning-show battle royale. Viewers will cast their votes with their clickers Tuesday. If you're a Couric fan who misses those bygone mornings on the "Today" show, then click to "Good Morning America," where Couric, now an ABC star, is subbing all week for co-host Robin Roberts.