Sky Captain & The World of Tomorrow comes out in North America today, and the reviews so far are not bad. PeteyG found an article that discusses how it is the first feature film to utilize entirely computer generated backgrounds. While they are heavily promoting this fact for Sky Captain, we all know that Wing Commander 3 used this method a full ten years ago.
"Sky Captain and The World of Tomorrow" is the first feature film to be shot entirely against a blue screen with backgrounds filled in later using computer imagery. Given recent technological advances, a film done like this was just a matter of time.
You can find the full article here. A more appropriate question might be: Given the amount of time blue screen backgrounds have been used in film and video games, what took them so long?