Doggone It: John McCain’s plans to appear on Late Show with David Letterman appear to be falling through, but the bottom half of his ticket may have finally firmed up her own late-night gig. According to Cindy Adams, vice presidential candidate Sarah Palin will definitely be appearing on Saturday Night Live at the end of the month. “She has already OK’d it,” Adams says confidently. “She’s booked. It’s confirmed. Done deal. Sketches are being sketched as we speak.” Adams says we can expect Palin to cameo on the Oct. 25 episode and that her rehearsal time has already been penciled in for Friday the 24th. Nor word yet on whether Tina Fey has been booked to appear, but if she’s too busy, might we suggest Betty White instead? [New York Post]