I've heard rumors about Apple looking to get in on the console action. Honestly, I think that would kill the company. However if they did, I see it like this:
Nintendo vs Apple - geared more toward casual gamers and the younger crowd
Microsoft vs Sony - geared more toward hardcore gamers and the older crowd
I'm not a big fan of Apple, but I think it would be a fatal mistake to try and enter this market. The only thing keeping them afloat is the iPod and the iPhone..if they had to funnel money into a console that WOULD fail, it would spell the end of the company.