Yahoo News (AP) features an interview with John Williams, who talks about the score for Episode III. Here are a couple of the questions he answered.
AP: "Revenge of the Sith" tells how Anakin Skywalker turns evil and becomes Darth Vader. How do you illustrate this musically?
John Williams: I've had a little musical fun with Anakin's theme, which appeared in one of the earlier films. ... I've had to work (the music) to accompany the scenes of where he's turning (from) the honorable ways of the Jedi and is becoming lost in this imperial dark side of things. So it's been a nice musical exercise. As with most of the "Star Wars" material, it's more like an operatic musical function than perhaps most film scores.
AP: How long did you spend on this "Star Wars" episode?
John Williams: We recorded 2 hours and 10 minutes of music and I think I began writing this in ... late September of '04, and we recorded this in the early part of February of '05. ... Ten or 12 weeks.
Hit the link above to read the rest of the article. Thanks to Jay for the alert.