Btw, this functionality + the option to designate a thread as a question is a feature of community server 2008.5.
Also, in CS 2008.5 the best answer is moved up
under the first post and is marked as such (although they should actually move it and not duplicate it as it is messy when the best chosen answer is the next post). See this post as an example:
http://dev.communityserver.com/forums/t/504289.aspx