Why? No idea. There was no inkling of it on Google News earlier today. It sounds from the clip like he was let go, but he signed a four-year contract extension in 2008 so I’m not sure how the mechanics of firing him would work. Could be that he resigned, but there’s been no indication of which I’m aware that he was considering that.

Unhappiness with Olby among MSNBC employees has been rumored for ages, and some speculated last year that Comcast might want to “rein in” MSNBC, but as I say, this is all just theorizing at the moment. In fact, even Mediaite, which should have access to insiders at MSNBC via Dan Abrams, only has the company’s vague official statement at the moment:

“MSNBC and Keith Olbermann have ended their contract. 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.”

Stand by for updates galore, no doubt. Howard Kurtz says Lawrence O’Donnell’s show will move to 8 p.m. and Ed Schultz will move to 10 p.m., which leaves a hole at 6 p.m. Is Alan Grayson ready for his close-up, Mr. DeMille? Or is Clarence “Supercop” Dupnik about to take over the role he was born to play?

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Update: Gotta say, assuming that they fired him, he reacted with a lot more dignity than I would have expected. No indignant Beale-esque jeremiad about corrupt corporate powers who can’t stand to hear “truth”?

Update: A half hour after the announcement and still nothing on Twitter or from any of the major cable news blogs about what happened. Evidently this is a shock to everyone, including people with good sources.

Update: Greenroomer Patrick Ishmael writes, “I guess @keitholbermann is taking this whole ‘No Palin February’ thing pretty hard.”

Update: The Chicago Tribune notes, “The surprise announcement comes as telecommunications giant Comcast is said to be near to closing its deal to acquire control of MSNBC parent NBC Universal from General Electric.” A network spokesman tells the AP that that had nothing to do with it.

Update: Anderson Cooper is using the F-word, but it’s unclear if he’s speculating or has the scoop.

Update: A shrewd prediction from Greg Pollowitz. Olby will be back on your screen, but it might not be your TV screen.

Update: If you want to follow along, here’s the “p2” Twitter feed, which captures tweets from progressives. They’re … not amused.

Update: Here’s the best information we have thus far, which still ain’t much:

The host, who has had a stormy relationship with the management of the network for some time, especially since he was suspended for two days last November, came to an agreement with NBC’s corporate management late this week to settle his contract and step down.

More:

MSNBC announced that “The Last Word with Lawrence O’Donnell” would replace “Countdown” at 8 p.m., with “The Ed Show” with Ed Schultz taking Mr. O’Donnell’s slot at 10 p.m. Mr. Olbermann did not discuss any future plans, but NBC executives said one term of his settlement will keep him from moving to another network for an extended period of time.

He’s not going to Fox, needless to say, and after so many horror stories from people who’ve worked with him, presumably even CNN isn’t that desperate for a ratings boost. Where could he go?

Update: Via Politico, the plot thickens:

The mutually agreed-upon departure was a stealth move, MSNBC insiders told POLITICO, with many top executives and on-air talent kept out of the loop as the decision was made. It came, one insider said, “Out of the … blue!”

Yeah, really? Halfway through his contract, both he and MSNBC suddenly upped and decided that everyone would be better off if the guy with the biggest ratings on the network found a new job?

Update: Another source tells Kurtz that it wasn’t about Comcast:

A knowledgeable official said the move had nothing to do with Comcast taking control of NBC next week, although the cable giant was informed when it received final federal approval for the purchase that Olbermann would be leaving the cable channel. This official described the dramatic divorce as mutual.

Maybe they’re playing semantic games here? Comcast might have told Olby that he can either quit or stay on and tone it down, leaving the choice to him. That would, in theory, make the divorce “mutual.”

Update: A reasonable deduction from Mediaite:

Sources close to the situation have told Mediaite that there is no question that Comcast had expressed concern about Olbermann. Hardly surprising since even last July Olbermann famously claimed via Twittter that Comcast wanted “MSNBC to go more liberal.” The public flaunting of the future bosses could not have sat well with the new management, who seemed to have seen the red flags from the beginning.

The virtual war in which Olbermann was engaged with his bosses at MSNBC and NBC News could not have been something that Comcast wanted a part of. And while thus far there is no specific evidence that Comcast had a direct hand in this development there no almost no question that Comcast provided some sort of support to NBC to end Olbermann’s contract, and action that Jeff Zucker might not have supported.

Update: As of 11 p.m., Olbynews has slowed to a crawl. If we’re going to get the big scoop on what happened, I assume it’ll come tomorrow. I’ll be watching the wires for another hour or so and will update here if new details break, but if not, this is the last update for tonight.

Update: No sooner do I write the last update than Mediaite drops this. Canceled on account of jackassery?

Sources tell Mediaite Keith Olbermann and MSNBC were headed for a breakup long before Comcast’s rise to power, but clearly something set the divorce into motion quickly today, with network promos set to run touting Olbermann’s role in MSNBC’s coverage of next week’s State of the Union address–and, notably, a Keith Olbermann promo running on MSNBC in the hour after the host signed off and left the network…

In recent weeks, sources tell Mediaite there have been meetings on the topic of Keith Olbermann and his future at the network. Did Comcast–as many Countdown viewers seem to suspect–order Olbermann out? It appears that the end of the Olbermann era at MSNBC was not “ordered” by Comcast, nor was it a move to tone down the network’s politics. Instead, sources inside the network say it came down to the more mundane world of office politics–Olbermann was a difficult employee, who clashed with bosses, colleagues and underlings alike, and with the Comcast-related departure of Jeff Zucker, and the rise of Maddow and O’Donnell, the landscape shifted, making an Olbermann exit suddenly seem well-timed.

Yeah, Sam Stein at HuffPo is also touting Zucker’s departure as key to Olby leaving. Quote: “Zucker was Olbermann’s protector there.” But the mystery lingers: Why was Kayo’s departure today so sudden? Did he find out about the meetings that were being held to plan his exit, and decided to quit before he was fired?