Right now this forum is incorrectly allowing anyone who has pre-ordered Warlords of Draenor to post. The intent is, as with all past expansion test forums, that only those with actual access to play the Alpha/Beta have posting privileges.
We're in the process of developing and testing a fix, and once deployed anyone without Alpha access will find that they will not longer be able to post. Full visibility of the forum will continue, and we invite everyone to come and read feedback from current testers as well as developer posts.
The current number of testers is extremely limited, but we will of course be expanding the number of testers as the Alpha and Beta progress toward release of the expansion. For more info on the current test and how you can get an invite, head to the announcement post in the General forum