Libya: Setting a precedent?

So, now that the free world, lead by the US (well, most of the Tomahawk missiles have been their's), has the precedent been set? Are we now obligated to deal to every despot who attacks their own citizens?

NOT PC has the perfect quote:

It is not a free nation's duty to liberate other nations at the price of self-sacrifice, but a free nation has the right to do it, when and if it so chooses…

Does donating to charity set a precedent? Yes, but I have every right to choose not too the next time. It just depends on the circumstances.