This isn't a bad move strategy wise. If the Apple performance is as awesome as is rumoured and hype, there are going to be a lot of people looking for new arm chips, with no obviously ahead players. nVidia has looked a couple of times at building their own x86 core, and ARM cores may be a better bet.

At this point - AMD, Intel, Apple are all looking at fully integrated APU/CPU/GPU stacks. That leaves NV out in the cold if they don't do something.