Stephen Wolfram is awesome, I didn't know he tracked his own stats like that! I'm quite surprised how many people are using treadmill desks.. Micheal Arrington of TechCrunch, and Kevin Rose (Digg founder) also use them.
Nice study, also.
Steelcase makes a sit-to-walkstation as well. One I've been looking at is: http://www.thehumansolution.com/uplift-treadmill-desk.html
- or potentially building my own. It's not a very popular thing in Canada yet... but the treadmill shop I called this weekend mentioned that they had 3 people asking about treadmill desks this week, so something seems to be raising interest in them.
Here's a social network about it: http://officewalkers.ning.com/