[Update] Sony's Shuhei Yoshida has confirmed on Twitter that the PlayStation 4 will support up to four controllers at a time. This number is clearly dwarfed by the Xbox One's eight, but it's hard to imagine an instance in which you'd ever need more than four.
[Original] Microsoft has confirmed that Xbox One will support up to eight controllers simultaneously. In addition, the control pad will have a range of 30 feet.
Don't expect a bunch of games to support eight controllers, though. After all, the PlayStation 3 can handle seven controllers at a time and you'd be hard pressed to find many games that take advantage of that feature.
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