Birds of Steel. While notably not a part of the long-running IL-2 Sturmovik series, Birds of Steel does share its aerial combat and its WWII setting. The usual stuff is all here: historical and fictitious missions, lots of real planes, all spread across both single- and multiplayer campaigns. That multiplayer component includes co-op missions as well as your traditional all-out aerial dogfighting.
If a historically accurate WWII aerial combat game doesn't sound entirely thrilling to you, we'll give you another, admittedly biased, point of view from Konami Digital Entertainment GmbH's Martin Schneider: "For far too long, first-person shooter fans have been tied to the foot soldier point of view, but we aim to bring the seat-of-their-pants skill and daring of dogfighting and aerial combat to a wider audience." That wider audience includes Xbox 360 and PS3 owners, though Konami is notably shy about sharing a release window.