All AMD's APUs are is a chip with a CPU and a beefy GPU to back up the CPU. Mobile CPUs tend to already have GPUs, so that's that. This guy might help with the designs and such, but it's not like the APUs have some sort of architecture that separates them from any other CPU with an on-die GPU that uses the same CPU and GPU architecture(s). It's just a name for marketing to trumpet around, like how Apple doesn't want us referring to their Macs as PCs. The name might have come from the concept of letting the GPU act as an incredibly high performance FPU, but any GPU can do that if it's programmed for it.