Apple has released an update to its AirPort Utility app for the Mac, bringing it up to version 6.3. It adds the ability to extend a guest WiFi network across multiple AirPort base stations, support for WPS-capable printers and improved international support. It's a free download, as always.
The 6.3 update requires an Intel-based Mac running 10.7.5 or later. You can grab it right now through Software Update, or head on over to Apple's update site.