This is how Apple describes the update to version 6.2 of Airport Utility for Mac and 1.2 for iOS:
Use AirPort Utility to set up and manage your Wi-Fi network and 802.11n AirPort base stations, including AirPort Express, AirPort Extreme, and Time Capsule. AirPort Utility 6.2 contains improvements and bug fixes, including:
The ability to extend the Guest Wi-Fi network on a network that is configured with multiple AirPort Base Stations
The ability to add a WPS-capable Wi-Fi printer
Improved international support
There is another step required however to take advantages of these features, you must upgrade the firmware of your Apple 802.1.1n device to version 7.6.3, you can do this from within the Airport Utility. It is recommended that AirPort Utility 5.6 or later be installed before updating to Firmware version 7.6.3. Configuring the extended Guest network requires AirPort Utility 6.2 and Mac OS X Lion v10.7.5 or later.
While I don’t use the guest network feature I am delighted with the ability to add a WPS-Capable printer because it is a real pain to do it manually. If you are looking to add a WPS printer on the Mac version the function is hidden away on the base station tab on the menu bar. In the iOS version it is a clearly visible button on the advanced tab.
Now all Apple has to do is restore WPS for all devices. 🙂
The update to the Airport Utility will show up in Software Update on your Mac and the Firmware update can be installed from the Edit page for the device in the Airport Utility.