Delta is the latest with a Windows Phone app:
What is Fly Delta ?
Designed to make flying Delta Air Lines more convenient and rewarding, this free travel app helps you take care of key travel tasks on the go:
• check in for upcoming domestic flights.
• download mobile boarding passes (where available) to use at security and the gate.
• rebook on an alternate flight when yours has been canceled or delayed.
• launch an interactive seat map and pick your seat.
• check your position on the upgrade or standby list.
• see the latest flight status and get terminal and gate info.
• map flights en route with an interactive flight tracker.
• see your SkyMiles balance and current Medallion status.
• save a photo and make note of your parking spot.
You can even connect with the Delta app onboard your next flight for free through Gogo Inflight Internet.
In the next release of the Fly Delta Windows Phone 7 app, look for tools to:
• pay baggage fees and track checked bags.
• find your gate on a zoom-able airport map.
• browse Delta Sky Club™ locations and amenities.
• explore Delta’s fleet and see plane layouts.
Visit www.delta.com/app for more information on upcoming releases and versions for other mobile devices.
You can grab it here.