Personally, it looks like AMD is gaining ground on Intel thanks to their ownership of ATI. AMD has demo'd two different families of APUs already (combined CPU/GPUs).

ARM is at a disadvantage architecturally when compared to X86. Its a cruder processor and some of its features lead to significantly less dense code.
But ARM is gaining ground constantly. However, if you were to compare current ARM offerings and processor like those I referenced earlier, X86 still has a performance edge.

I don't see any clear winner here yet except the consumer. When there is competition, increased innovation occurs and prices are lower.

[ Edited by Jim on 2011/1/21 20:40 ]