I recently published an article on SearchWinDeveloment. It explains how we (the NDepend team) are using NDepend to analyze the NDepend code to avoid regression bugs while adding new features.

More specifically, we are using the possibility to compare 2 versions of our code base. Then we focus our efforts on reviewing and testing the code that has been modified or that was added since the last release.  My experience always showed that the bulk of problems come from fresh code.

Of course, the preferred way to avoid regression bug is to have a high automatic test coverage ratio on the new code but it is rarely possible to have 100% coverage, especially on application with a complex UI.