Revenge of the Sith can just as easily be taken as a classic warning to leftists: seize power in the name of doing good and you will become a tyrant, no matter how noble your intentions. Lucas might not have intended it, but the warnings in the film seem to apply more to the Left than the Right.
The series can be taken a lot of ways, but it isn't really about politics. It's a classical tragedy about one man being toyed with by the fates.