answers.ros.org has been created with the goal of decreasing the volume of traffic on the ros-users as well as providing an easy place to archive common answers to questions.
We have been seeing a number of repeated questions on the ros-users mailing list as new people join the community. The hope is that this forum will allow easier access to older posts, as well as by slightly more dynamic and browseable.
We also hoping to merge this site with the Troubleshooting and FAQs for individual packages which developers have not filled out as well as they might have. Questions relating to specific stacks should be tagged with the stacks name. And questions relating to a specific package should be tagged with both the stack and package name if possible. If you find a question useful please upvote.
In general ask questions here, on answers.ros.org, for which you think there is a single answer. If you would like to start a discussion or an open ended question you should use the mailing lists.
Kinect related things definitely just tag with "kinect" and pcl with "pcl" as the package tagging guidelines above would suggest.
PS We will be updating the faq linked at the top with this and other questions about how this site works. If you have more for now go ahead and post with "answers.ros.org" as the tag, and we'll consolidate them as seems appropriate.