The Site Management forum is very useful but I feel that its very general. A dedicated CMS forum will definitely be of use to many members and bring in a lot of outside traffic because as you well know, CMSes are getting very popular because everyone likes the thought of having content separate from design which facilitates everything. So having a spot on the forum will help a lot of people including myself because I've had certain issues where I had to go through dozens of sites and forums to find the answer, whereas having it all in one place will definitely be a plus and I will gladly share what I've learned in both Joomla and DotNetNuke in both Windows and Linux environments.