The changing of the guard in latenight TV continues with David Letterman today telling a studio audience that he plans to retire at the end of 2015 after what will be 22 years on CBS.
The 66-year-old comedian is network TV's longest running latenight host.
Letterman started his latenight run in 1982 on NBC and switched to CBS in 1993 as part of a highly publicized battle with Jay Leno to be the successor to Johnny Carson.
Leno got Carson's "Tonight" show chair, and Letterman went to CBS.
Leno retired earlier this year at NBC and was replaced by Jimmy Fallon.
Letterman's contract runs through 2015 at CBS.
He made the announcement Thursday...