It's been in closed beta for a couple years now IIRC. His approach is very different from what's prevalent in the industry today - he prefers to only release a product that's reasonably well done, instead of frustrating his audience with a buggy moving target. That's why the language is in its seventh/eight year of closed development at this point.
Last time I checked (a couple of months ago) there wasn't even a formal language spec yet.