From http://blogs.atlassian.com/2011/06/atlassian_answers_get_your_atlassian_questions_answered/:
We’ve spent a considerable amount of time developing a design for Atlassian Answers that we think hands down has one of the best end-user experiences of any comparable tool. Atlassian Answers is powered by OSQA, an open source Django (Python) application developed and supported by the folks at Dzone.
Rising Stars are recognized for providing high-quality answers to other users. Rising Stars receive a certificate of achievement and are on the path to becoming Community Leaders.