I remember seeing a post saying Beta will be available in early 2015. Now, it is about June.. I wonder when will Beta be released. Or maybe the administrators and some others is having closed beta.

It's a general purpose forum that's intended to compete with others. Once the theme engine is in place, we'll be able to get more involvement from the public. For now, you can check out the source. On top of that a beta is being evaluated with the staff at this point so please sit tight.