USB and Power Adaptor
The Kinect uses a non standard USB pinout and combined power adaptor design - designed to mate with a special socket on the new Xbox 360 Slim Models.
This page to document DIY mod to achieve the same as :
The Power/USB adaptor is bundled with the Kinect sensor only if purchased separately - if you have acquired a kinect as part of a xbox360 slim bundle; or by other means - there is no adaptor - and they are not commonly stocked at retail stores.
A user has identified the Pinout as below