Some new information on the controllers has been made available to us from a variety of sources, including Czech site Jablickar.cz, which reports that Apple will team up with both Logitech and MOGA to produce the upcoming controllers. While no details on design have been leaked, Apple did provide two reference images to developers displaying a standalone handheld controller and an iPhone enclosure.
Both of the aforementioned companies already produce gaming controllers for use with PCs and Android. Major gaming companies like Gameloft, Mad Finger Games, SEGA, and Rockstar Games all offer support for MOGA's Android controllers, suggesting that support for Apple's upcoming controllers is likely too.
Games that include support for the controllers will be required to support traditional touch-based gaming input as well. Though Apple has prototype controllers on-hand at WWDC, the company is expecting the third party controllers to debut in the fall.