This is Kinect. It is Microsoft's new motion controller system. You cannot sit on top of it. Well, you can, but you'll break it.
You can sit on a sofa. Right now, I am sitting on a sofa! Amazing.
For snots and giggles, this comparison between a sofa and Microsoft's Kinect has appeared on the internet. Just because Kinect apparently doesn't play nice with couch potatoes, that doesn't mean it cannot be compared to couches.
A 90 dollar sofa? Really? I guess... And Kinect can apparently support more than 2 people, so that should be corrected. Also, that last comparison isn't quite fair. Hardcore games like Child of Eden can be played on Kinect. Other hardcore games can also be played on a sofa. Hey-yo!