Apple’s iOS 4 is set to launch publicly today, and many app developers have been hard at work updating their apps to support the new iOS 4 functions. Today, one of the most popular apps that exists, Pandora, has been updated to allow for backgrounding on iOS 4. What does that mean exactly? Well, now you can fire up Pandora, pick a station, and the music will keep playing, even if you leave the app (similar to iPod.) A double-tap of the home button, and a swipe to the left, will give you widget controls to let you control the music without even going back into the Pandora app. You can get the update now, or if you don’t have it yet, you can download Pandora for free.

[Thanks, Jason!]