From Ben Goodger's blog:

Brian has been one of the most crucial elements to the success of Mozilla software over the past few years, with his work all over the Mozilla code - I remember him first adding mousewheel support back in 2000, then moving with tenacity into many other areas of code. Over the past few years Brian has been invaluable to Gecko development, working on many areas that have resulted in performance improvements and new features, while also having time to work on application level features such as the Linux installer, GNOME integration and the password manager. Great to have you on board!