Here we have yet another nasty surprise. For some people, this won't be an issue, but for others...it sucks.
The bundle didn't come with this cable, and as a result, you can't buy yourself a new Xbox, give your old Xbox to your wife with the Kinect, and have them work. The Kinect with the Xbox bundle, must be used with the new model Xbox.
As far as we can tell, Microsoft has no plans to offer this cable as a separate purchase. Fail.