When Kinect launched for Xbox 360, it was immediately compatible with Windows PCs. When Xbox One's Kinect launches, that won't be the case.
Microsoft confirmed that the Xbox One's Kinect sensor was built specifically with the new console in mind, meaning that it has a proprietary connector that the company does not intend to release a USB adapter for. However, a next-generation Kinect for Windows sensor is in the works that will serve that particular niche.
Honestly, this news isn't particularly surprising. The first Kinect released as a peripheral several years after the Xbox 360. Microsoft intends for the Xbox One's Kinect to be an essential, integrated component of the console. Giving users the option to take it into another room, leaving the Xbox One a useless brick doesn't seem very cohesive to Microsoft's vision.
Microsoft: Kinect for Xbox One will not work on PCs [Ars Technica]