David Letterman made a surprise appearance at CBS's upfront presentation Wednesday to poke fun at his network and his so-called rivalry with CBS chief Les Moonves. "We're all excited to find out what this year's Wolf Lake will be," Letterman cracked. A taped segment showed Moonves washing Letterman's car and holding cue cards on the Late Show set. (Despite all the silliness, it was clear these two will never be friends.) Meanwhile, based on clips of CBS's new fall shows, Monday night sitcom Still Standing (starring The Full Monty's Mark Addy) looks to be a winner, while Sunday night comedy Bram and Alice which is being paired with a relocated Becker from 8-9 pm/ET has a big "L" written on its forehead. Somewhere, Ted Danson is very angry. For a glimpse at CBS's new schedule, click here.