Ken Levy points to a new site run by Ronny Kohavi, a "general manager in Windows Live division" at http://exp-platform.com/ According to Ken's post:

The Experimentation Platform will enable product groups at Microsoft and developers using Windows Live to innovate using controlled experiments with live users. Such a platform will enable testing new ideas quickly using the best-known scientific method for establishing causality between a feature and its effects: randomized experimental design.

Learn a bit about the Expirimentation Platform, check out the job listings, or check out some "cool things about Microsoft and Windows Live" on the site, which is built using Office Live.