Mmozeiko's summary is correct. I think it may be interesting to do an Android port, so that is very much in the running for things to do in the future. Anyone can develop for Android, and you can install Android binaries on Android phones without permission from Google, so it fits with the open, educational model of this project. How you would play this game on a phone or tablet, I don't know, but it could certainly be played on Android "console" devices like Ouya and so on that have an action-game-appropriate controller.
iOS, on the other hand, is a closed ecosystem that requires paying Apple for developer access and getting Apple's permission to ship binaries. I personally strongly dislike this model of computing and feel that it is philosophically against what this project is all about. The whole point of Handmade Hero is to make people comfortable with tinkering with the computer hardware that they own, making their own programs, and empowering them to understand and control the computing world around them at every level.
Similarly, I will not be doing a port to the closed Windows 8 "Store" ecosystem, since it has the same restrictions as iOS, just with Microsoft as the gatekeeper instead of Apple.
- Casey