We do not have current plans to develop a GTD application for the iPhone, iPad or iTouch. If that changes, we will make an announcement about that on our websites. We do not endorse or recommend any particular iPhone, iPad or iTouch Tasks application at this time, except for OmniFocus for iPhone, which is for Mac users only.
If you are looking for GTD action list management functionality for your iPhone (which is really just one component of your GTD system,) then please read the next question.
