Android-based IDEs already exist. I should know. I was looking for one the moment I bought my ASUS Transformer a couple years ago. I found the only thing I couldn't do with the device was write and compile programs. I would bring it to hacking sessions, but I couldn't test code on it. At the time, the only option was a text editor that could style and check code syntax.

The main downsides of these devices for programming is screen real estate, CPU speed, and support from major IDE/compiler vendors.

Example: https://play.google.com/store/apps/details?id=com.aide.ui