Microsoft has acknowledged that the video reflects "a concept we've been working on with partners," but warns that the video is dated and does not represent the product's current state. The keyword is "concept," which suggests that the Halo footage was added to demonstrate the Origami's capabilities. As such, this is not evidence that the game will be featured on the device. But, according to OrigamiProject.com, Microsoft is poised to make a major announcement this Thursday, March 2. Stay tuned.
It should be noted that the Origami appears to be a mobile PC, rather than a portable gaming device or media player. The device does not look to compete with Nintendo or Sony on the handheld gaming front, nor does it look to upstage Apple in the portable media market.