I quite like their AnswerHub, where you can ask the developers in several categories, but it is a bit different from a forum. threads are tracked whether answered or not, and you can reactivate it by further questions. it seems to be a good solution to manage questions and answers in a huge quantity, and they take it seriously. for example one of my crash reports was finally pushed towards the proper specialists when it was too tricky for the standard answering guy, and they could find a workaround what to modify in source code and ini files.

moreover, here users can get karma points if you ask/resolve something important, or if you answer other users' question. and you get badges for notable or popular questions. maybe it is good for the developers to track and know better their users personally. (I have 21+2+2 after 2 problem solving discussions.)