A recent update on the Battle .net website announces that Blizzard is getting close to releasing hearthstone: Heroes of Warcraft on phones. This would make the game truly portable... like a deck of cards!
Currently, in addition to the desktop version of the game, on the portable side of things, an iPad version of the game is already available, while touch capabilities for Windows 8 are now supported.
While it is disappointing to have to wait for all these versions, one thing that is great (or bad) about Blizzard is that it seems that they will not release a game until it is truly ready. In some case, they have completely axed games that they felt would not be awesome. In the case of hearthstone for phones, it probably won't get axed but instead, delayed until 2015.
Hopefully we will see some more about these developments at BlizzCon 2014, but in the meantime, Blizzard has left us with this awesome infographic about hearthstone.