Keith Olbermann signs off from MSNBC

(CNN) -- After eight years together, MSNBC and Keith Olbermann are parting ways.

A statement from NBC Universal revealed the move late Friday.

"MSNBC and Keith Olbermann have ended their contract," it read. "The last broadcast of 'Countdown with Keith Olbermann' will be this evening. MSNBC thanks Keith for his integral role in MSNBC's success and we wish him well in his future endeavors."

At the end of his show Friday night, Olbermann announced his departure in typical deadpan style, evoking scenes from the film "Network" and thanking viewers for keeping him on the air for eight years.

"In the mundane world of television goodbyes, reality is laughably uncooperative," Olbermann said before launching into a story about his exit from ESPN 13 years ago.

"As God as my witness, in the commercial break just before the emotional moment, the producer got into my earpiece and he said, 'um, can you cut it down to 15 seconds so we get in this tennis result from Stuttgart,'" he said, half-smiling, pausing for composure.

"So I'm grateful I have a little more time to sign off here. Regardless, this is the last edition of Countdown."

Olbermann thanked his crew and co-workers, with special praise for the man he called "my greatest protector and most indefatigable cheerleader," Tim Russert, the host of NBC's "Meet the Press" who died in 2008.

Olbermann was suspended for two days in November after the news website Politico revealed donations made to three Democrats seeking federal office. One of them was U.S. Rep. Gabrielle Giffords, who was wounded earlier this month in a mass shooting in Tucson, Arizona.

He gave $2,400 -- the maximum individual amount allowed -- to Giffords' campaign, as well as to the campaigns of Senate candidate Jack Conway of Kentucky and U.S. Rep. Raul Grijalva of Arizona. Conway lost his bid, while Grijalva and Giffords won.

NBC said the donations violated a policy that requires employees of the news organization to obtain permission ahead of any political donations or activities that could be deemed as a conflict of interest.

After his suspension, Olbermann gave an on-air apology to his viewers "for having subjected you to this unnecessary drama."

"It's not in my contract that NBC had rules about getting permission for making political donations, even though any rule like that in any company is probably not legal," he said on the program.

Olbermann complained publicly about his frustration with NBC's management. He made it clear that he resented the insinuation that he was attempting to hide his actions.

"When a website contacted NBC about one of the donations, I immediately volunteered that there were in fact three of them; and contrary to much of the subsequent reporting, I immediately volunteered to explain all this, on-air and off, in the fashion MSNBC desired," Olbermann said in a statement at the time.

He also accused NBC of "inconsistently" applying its policy and suspending him without first hearing his side of the

story.

Former MSNBC anchor David Shuster told CNN's AC360 that he was "shocked" by the sudden news of Olbermann's departure.

"You look at all of MSNBC's prime time -- Rachel Maddow, Lawrence O'Donnell -- I mean, they exist because of Keith, and Keith was the fundamental building block," Shuster said. "I just hope for Keith's sake that he's leaving on his terms, which it sounds like it was, in the sense that he was given time to say goodbye."