No release date yet.
If I may put in my personal opinion though lol.. the game is already very well balanced, and there seems to be very few bugs atm. The only ones I've found are an occasional crash with the client, and a bug that sometimes prevents ladder information being displayed (and friends list). Neither of which affect gameplay (well, i guess the crash would lol) and I imagine are already identified and being fixed. Given that mass beta invitations are going out and they're doing a sort of stress test on the system, and the feedback of the players, I wouldn't be shocked if release was just 2 months from now. Three months to play it safe. Any more than that, I think, would mean that Blizzard is holding off to make a significant change to.. something.
However, that's not taking into account all the stuff happening in Korea. So who knows.