Why can I not rotate my windows on my Vista Desktop?

In the User Interface Engineering lecture we discussed today input devices, especially to interact with 3D environments. In 3D environments having 6 degrees of freedom (3 directions in translation and 3 options for rotation) appears very natural. Looking back at 2D user interfaces with this in mind one has to ask why are we happy (an now for more than 25 years) with translation (in 2D) only and more specifically why is it not possible to rotate my application windows in Vista (or perhaps it is and I just dont know it). At first this questions seems like a joke but if you think more of it there could be interesting implication (perhaps with a little more thinking
 than this sketch 😉

Obviously people have implemented desktops with more than 2D and here is the link to the video on project looking glass – discussed in the lecture. (if you are bored with the sun sales story just move to 2:20): http://de.youtube.com/watch?v=JXv8VlpoK_g
It seems you can have it on Ubuntu, too: http://de.youtube.com/watch?v=EjQ4Nza34ak