PowerVR like the AMD Adreno is also integrated on silicon. All ARM-based processors are SoC (system on chip) and the GPU is an integral unit to the design. Thats why you can have good performance and yet a power efficient product.

Qualcomm has always been stucked with ATI/AMD GPU just like previous HTC products (which uses Qualcomm). You guys still remember the Tilt II do you. All users left without a properly working driver. PowerVR usually is with the TI OMAP, Samsung (and now PA Semi/Intrinsic/Apple) camp.