Keith Olbermann FIRED from Current TV -- Replaced By Elliot Spitzer

Keith Olbermann is officially unemployed ... again ... cause the political host has just been FIRED from his gig on Al Gore's Current TV network.

Olbermann had been hosting "Countdown" on Current TV since June ... right after he got the chop over at MSNBC.

Now, it seems he's once again pissed off his employer ... 'cause Al Gore just released a statement in which he explains, "[Current TV] was founded on the values of respect, openness, collegiality, and loyalty to our viewers. Unfortunately these values are no longer reflected in our relationship with Keith Olbermann and we have ended it."