Announced at PAX East back in March, Hearthstone: Heroes of Warcraft is set to become the first Blizzard title that's announced and released in the same year (well, at least as far back as we can remember). On the official blog, they know state we're not far away from a beta.
"We're making good progress, and while we definitely won't fix every bug before releasing the beta, we do think it's important to address any issues that would pull focus away from the core game experience. What that means is that we're not days away from launching the beta, but we're not months away either".
At first the beta will be on an invite-basis only, but it will then progress to an open beta. Perhaps Gamescom is a good place to announce the start of the beta, what do you think?