Blizzard has confirmed that Hearthstone: Heroes of Warcraft is now in open beta across Europe. The card game, which is out now on PC and Mac (and will follow to Android and iOS devices in the future), isn't the finished article yet so the beta release comes with a couple of caveats.
Blizzard has "no plans to perform any more card wipes", but doesn't go as far as ruling them out. They also state that they may have to temporarily disable open beta account activation if "smoke starts curling out of our servers due to unexpectedly high demand". But that's enough from us, you can download the client here and get playing.