I'ld like to suggest that you make it easier to find SLG on the website, because I can't find it. Why not simply post a small link to it on the download page?
Because it's not meant to be a released and supported software. It's a testbed for future LuxRender features. Admitedly it's quite powerful and useful on it's own, and it's freely available in the GPU acceleration forum: viewforum.php?f=34