I guess a "readealist" (realist/idealist) reading of the US empire shows it's better to keep your expectations of its generals low, and your hopes regarding the people high.
Just when we thought the revolution sweeping through Tunisia and Egypt has spared us the false choice between oppressive autocrats and imperial cynics, a defiant Gaddafi presented us with an ultimatum: "My rule or rivers of blood." 

Devoid of any moral consciousness, he didn't hesitate to use the bloodiest means against his own people. His actions, reminiscent of those by the foreign colonialists he has often condemned, have provided them with the pretext to intervene once again in the region.
It's important to look beyond Libya to the greater region where overzealous western intervention could only hamper the spirit and authenticity of the Arab revolution.
Be that as it may, the endgame hasn't changed. Gaddafi must go. Not because Obama or Cameron said so, rather because the courageous Libyans, like other Arab revolutionaries, insist "the people want to bring down the regime".