My Mom got a Kinect and it's pretty darn cool. I didn't think it would be all that great, because there was the Wii already. It blows the Wii out of the water. It's so much awesome-r. Take the idea of motion control and then the idea of holographic interfaces and the Kinect is definitely the "Kinect"-tion between the two.
She bought Dance Central which has popular songs and you learn the dance moves and then perform it. The songs are rated from very easy (0 stars) to very hard (5 stars) then there is a difficulty setting as well (easy, medium, hard) and let me tell you it is HARD and fun! I was sweating up a storm. It takes pictures of you as well while you are dancing and puts them all together.
I did it for half an hour and earned 5 activity points. I did 6 songs, 2 times each once on easy and once on medium. It was pretty awesome. I totally didn't feel like I was working out even though, it was definitely a work out. I am sore today.
I totally want to go out and get a Kinect. :)