Are dictatorships legitimate governments?
 

Should they be permitted in the UN, for example?

not all dictators are bad.. some ppl still like bush :Graucho

Dictatorships are needed in some countries, where a democracy would bring on chaos because of all the warlords and different religions and stuff (see iraq)

Only because you haven't started any yet. ;-)

No. It is the duty of the free world to work to free the oppressed one way or another in my opinion.