In North America at least
Attention North America! Hearthstone: Heroes of Warcraft is now in open beta. Blizzard has opened the doors, and best of all they won't be doing anymore wipes, encouraging players to amass their collection.
The open beta will roll out for other regions within the next few days, and Blizzard will be announcing specifics on all that soon. Blizzard also warns that they may have to temporarily disable open beta activations if servers starts bursting on fire from all the attention the game will see.