Originally Posted by
Valyrian Stormclaw
It's the legal release date, according to the ToS, meaning that it the absolute latest the expansion will be released.
We already know that there is a very high chance that the cinematic will be shown at next month's Gamescon, and that more and more people are being invited to the beta. We also know that the alpha that was announced was actually just the early beta, as apparently the game was in in-house alpha for over 6 months before that at least.
Chances are it will be released sometime in October or November. Blizzcon will undoubtedly show off 6.1 and 6.2 and such.