NintendoWeb recently conducted an interview with the game's co-director, Brett Tosti. There are 2 parts; part one and part two.
BT: Well, even from Rogue Squadron to Battle for Naboo you probably saw a greater sense of realism; we did it from the music side and tweaked the game engine. Further now on the GameCube, the engine that we are using for Rogue Leader is allowing us to get a new sense of immersion so you feel like, ?Hey, this looks like the movie, but I?m playing it!? It?s sometimes almost hyper-real.