Rather recently, American Airlines released an iPhone app that offers quite a few nice features for the AA traveler, including flight status, boarding pass access and Soduku. With the exception of that last feature, travel app Kayak offers many of these features already, though it's not stopping other airlines from following suit.
Just the other day, a Delta executive mentioned in a short interview that a Delta iPhone app is on the horizon. It's not clear yet what kinds of services and features the app will provide, though it's a safe bet the American Airlines app will give you a dece
