From The New York Times:
ESPN is expected to announce on Wednesday that the former network mainstay Keith Olbermann, who contentiously departed in 1997, will return to host a one-hour, nightly show for ESPN2 later this year, according to three executives with knowledge of the deal but not authorized to speak about it publicly.
ESPN commercial from 1997:
Update: Wednesday, July 17, 2013 - 6:27 p.m. ET: