What theories are there in explaining the formation of the Pluto-Charon system? After reading the question and answer to Effect of Charon on Pluto, a further question is this: how is the Pluto-Charon relationship explained?

Specifically, what theories are there in how did the Pluto-Charon system was formed?

Additionally, does this explain the presence of other moons (Nix, Hydra etc)?
The favored theory is a giant impact, at the end of the final stage of planetary formation (Canup, 2005). A "giant impact" is a collision with an object of a comparable size of the planet. That is also the most probable scenario for lunar formation (Canup, 2004).