According to a press release from Imagination Technologies Group, Apple is "subscribing for" 8,200,000 new shares of Imagination Technologies Group which means Apple will have an ownership interest of 3.6% in the company. The press release also reveals that Apple is a licensee of Imagination's technology.
This is the first public confirmation that Apple is both a licensee and investor in the company which is responsible for the PowerVR 3D chipset for the iPhone and iPod Touch.
In September, Imagination Technologies announced that they had secured a new "multi-year, multi-use license agreement" with an unnamed company that gave access to both current and future PowerVR graphics and video cores. Apple was speculated to be the licensee at that time.
Combined with the acquisition of P.A. Semi and ARM licensing, it seems Apple has assembled everything it needs to build out new custom iPhones, iPod Touches or other mobile devices.