XNA Blocks with InterKnowlogy

Here's something fun. Take a developer and a few hours time and you've got the app below from Rodney Guzman with InterKnowlogy. The app is a bunch of cubes in a box that you can interact with your hands. What's great about this app is that it shows the power of having a vision system in Microsoft Surface. Ordinary objects, like the dry erase pen, work just as well as hands and fingers. There's nothing revolutionary about the app, but it's a great example of how XNA on Microsoft Surface makes for quick and engaging applications. What's next?