More David Letterman retirement jokes from Friday's 'Late Show'

You may have heard that David Letterman announced his retirement yesterday, and as any Letterman fan well knows, there's nothing like material that's generated by your own life (or in this instance, Dave's...). He taped his Thursday "Late Show" Retirement Edition yesterday at 3:30 p.m., and then promptly taped the Friday edition at around 5 (or thereabouts...). Here's a clip from tonight's show, and yes -- expect retirement jokes, good ones...Billy Crystal appears tonight as well; as has been noted, Crystal appeared on Jay Leno's last "Tonight.:"