He started the TouchDevelop project, which enables end-users to write programs on mobile devices. This project brings the excitement of the first programmable computers to mobile devices such as smartphones.
He is leading the Pex project, an automatic test case generator for .NET applications. Try out Pex on the web: www.pexforfun.com
Previously he worked on AsmL, and later on the model-based testing tool Spec Explorer.