Keith Olbermann abruptly announced his departure from MSNBC tonight. Thus far, Olbermann and NBC executives are staying mum about why the host of MSNBC’s highest-rated program is leaving the cable channel, but I’m sure we’ll know the reason soon enough. (Of course, there is plenty of speculation, including the NBC Universal-Comcast merger made official earlier this week.)

Knowing Olbermann’s history of burning bridges with past employers, I’m willing to bet that he soon will start lobbing metaphorical bombs at NBC.

I used to watch Olbermann, mainly during the Bush administration when he seemed to be a voice of reason among television pundits. But over the years — not coincidentally as his popularity and ratings grew — Olbermann became increasingly full of himself, and it showed on his program. The last straw for me was his weekly “Fridays with Thurber” segment, which understandably began as a therapeutic homage to his late father, but soon grew into a months-long exercise in hubris. After all, did Olbermann really think anyone wasn’t changing the channel as soon as he started those segments?

As far as I’m concerned, Chris Matthews was (and still is) the only primetime host worth watching on MSNBC anymore. (Of course, I watch the cable news networks more for news and analysis than the hyperpartisan stuff they air during the evening hours.)

I’m curious what you think about Olbermann, his sudden departure from MSNBC, and the future of MSNBC’s primetime lineup. Please post your thoughts about any or all of those subjects.