Apple has filed a patent application for techniques for providing input to interactive and multitasking applications, especially in regards to gaming.
The application appears specifically applicable to portable devices, where screen real estate is a premium. From the application:
A location on the input area can be designated, for example, for a gaming application if input is received in a particular manner different than that designated for the non-gaming application (e.g., tapping or touching the region would send input to a gaming application, but pressing would result in a media player function)
In general, Apple focuses on being able to control background applications via the same input surface without having to navigate away from the foreground application. For the iPhone/iPod touch, the patent is similar to the home button double-click functionality, but the touch screen would be utilized.
The application was originally filed in September 2006 and was published today.
Raw Data: Patent Application #20070279394