Kinect only supports two players, Move supports two-ish

[makingmusic476]

In case anybody else doubts the veracity of the claim that Kinect only supports a maximum of two players, this is from Majesco's press release for Zumba Fitness:

Players can also grow that party at home with up to four players on Wii™ and PlayStation Move, and up to two players on Kinect for Xbox 360.

Four players on Wii/ps3, two on 360.