We should implement next/prev (tab) and direction (d-pad) navigation of focusable controls, and ensure that everything is keyboard-accessible.

From http://developer.android.com/guide/topics/ui/accessibility/checklist.html:

Make sure users can navigate your screen layouts using hardware-based or software directional controls (D-pads, trackballs, keyboards and navigation gestures). In a few cases, you may need to make user interface components focusable or change the focus order to be more logical for user actions.