This will be supported probably some time later this year — we are in the process of changing OpenSprinkler hardware to use modularized design, that is, it will have a main processor board, plugged into a power+driver board. This will allow all OpenSprinkler hardware (including OSPi) to share the same power+driver board). And we will be redesigning the OSPi board to follow the same modularized design, that way the OSPi board will also have LCD and buttons, like the standard OpenSprinkler has.
But I really think that emphasizing on button control is a step backward. I just commented on another thread that the whole point of OpenSprinkler is to provide a web-based user interface, which is a lot easier to interact with than traditional button-dial based interface. I simply could not remember how to use those buttons and dials (or in what sequence) to change settings. These are terrible user interfaces that a web-based sprinkler controller is trying to replace. So I am really reluctant going backward to reproduce these traditional user interfaces.