GameFront is reporting on a website that is know for game leaks and refers to a email sent to the website owner back in August from a Blizzard source that reveals everything that was announced at last weeks Blizzcon. The email is dated Aug 17th, which of course be photoshopped, however if you look at the image upload date, it was 2 months ago.
The email shows that Blizzard was originally supposed to announce the Diablo 3 release date during Blizzcon, however in late September it was delayed to early 2012, so that’s mostly likely why it wasn’t. The email also shows that the tentative backup date was originally set for Jan 17th. Does this date remain as the backup release date? I don’t know, but it’s a pretty good estimate at worse.
Looking at Blizzard release schedule over the last decade we can see every game and expansion has been released between Nov 14th – Jan 16th and June 29th – July 5th. So a Jan 17th backup date is looking more and more legit. That’s enough to convince me and if it’s not exactly the 17th, I doubt it will be much further out.