I believe Win 8 was released to the public in October, and RTM'd in August. I just checked my TechNet account and I got my Win 8 keys 8/15/2012, the August/October dates mentioned seem to follow that pattern. I would not be surprised to see MS 8.2 next year and 8.3 the following.
I know this is a windows 8 thread but I was referring to MS past time line that has happened, not try to predict what will happen.