Southwest Airlines has issued an update to its iPhone and iPod touch app that should make the lives of several frequent travelers a bit easier. The company has added mobile boarding pass support to the app for 28 airports, which is up from the previously supported handful of airports. Mobile boarding pass functionality allows travelers to pull up their pass on their phones to be scanned upon check-in and security checkpoints at airports. Some additional features to make the user-interface simpler and more helpful have also been added in this 2.4 update.