The new app, which works on both the iPhone and iPad, lets you gain access to your wireless network and tweak the settings of your routers and other wireless devices, as long as they're Apple-made.
So if you've got an AirPort Extreme, and AirPort Express or two and a Time Capsule, you'll be able to have access to all of 'em on your phone. It even has a pretty graphical representation of your network, which is nice if you've got a bigger/more complex one.
U.S. & World
You can snag the App in the App Store or get it by heading to Settings on your device, go to your WiFi settings, tap the little blue arrow next to the currently active network and then hit the Manage This Network button.
Via 9to5 Mac