Apple released some iOS app store rule updates last week, including an in-app purchase change applicable to Hearthstone. According to the new rules, "Apps offering “loot boxes” or other mechanisms that provide randomized virtual items for purchase must disclose the odds of receiving each type of item to customers prior to purchase." This means items like Hearthstone's card packs must now have their drop rates listed on the app.
The wait is over! Hearthstone is coming for iPhone and Android phones today.