From an Associated Press article on Olbermann's departure:

David Brock, founder and CEO of the liberal media watchdog Media Matters for America, said Olbermann “led the charge” against “conservative misinformation in prime time.”

“Keith is an innovator and extremely talented broadcaster who showed there was a market for progressive views on cable news,” Brock said. “I'm sure we'll be hearing more of him soon, and I eagerly await hearing of his next move.”