Dance Central is clearly stamped with a "Requires Kinect Sensor" label, but the opposite is also true: Kinect requires Dance Central. Amazon is proving this point -- for a limited time, while supplies last -- by offering Dance Central for free (along with a bonus 240 Microsoft Points -- hello Paula Abdul!) with purchase of the 4GB Xbox 360 system bundle with Kinect, which already includes Kinect Adventures. Check out Amazon's promotion page for more details.
But here's the $130 question: What's missing from the picture? Ding-ding -- that's right! A hard drive. But Amazon has that on sale too, for just a dime under $91. So, buying the 4GB system bundle with Kinect and the 250GB hard drive separately is actually a shade cheaper than buying the 250GB bundle with Kinect -- plus Dance Central's tossed in there. That's a good deal.