Minecraft Pocket Edition – the diminutive iOS and Android version of the block-based phenomenon – isn't really Minecraft. At present, it allows players to build creations as they see fit, but lacks most of the features found in the PC and Mac versions. Namely, there is no Survival mode and all the things it entails, including item crafting, enemies, food, etc.
In a recent blog post, Mojang's Daniel Kaplan stated that the company plans to remedy the lack of Survival mode, at least partially. He stated that the goal isn't to completely "replicate" the full experience of Minecraft, as many features simply don't "match the touch platform." That said, many familiar features are planned, including animals, enemies and item crafting. Mojang is also "experimenting" with caves, though the implementation still needs work.
And, of course, Mojang hasn't specified when players can expect these features. That's okay though, because our full scale Battlestar Galactica is going to take a while anyway.