I don't think that any one form of government would be able to mantain control over a milti-planey society. That's not to say that any and every form of government wouldn't try they would just all fail.
There are plenty of people just within America that would say something along the lines of: "How can those fat cats in washington tell me how to run my business here in the great state of 'X'?" Now take that idea and expand it to a milti-planet sysem of colonies and civilaizations. How could a governmental body mantain control over an outpost on one of jupiter's moons?
I think that as man moves into the stars each new civilazation will evolve its own brand of government, even if that mean having basically no government.