Who could it be? Sony stands well enough alone.
Microsoft could use the help, don't want a repeat of the xbox's controller afterall, but microsoft seems to have their hardware fairly set as well.
Wouldn't it be interesting if sega talked nintendo into going powervr instead of ATI? Nintendo may have a good relationship with ati, but powervr seems to fit nintendo's plans better, actual high performance relatively cheap graphics chip for handhelds already available and they could probably produce a cheap yet competitive console chip as well...I don't know how nintendo feels about having essentially the same hardware as microsoft but less powerful....(actually, that might not be a bad thing for them, developers would do tons of quick ports to nintendo's system just to make an extra buck....a crappy port may be better than no port at all......nah, that just gives a system a bad reputation, better for a system to be known for its quality than the amount of ports it gets)