At the 2013 Moodle Moot in Spain Juan Leyva presented on MoodleMobile’s history and future (with Martin Dougiamas according to the presentation credits) and also highlighted the general requirements and abilities of being able to develop a plugin for MoodleMobile.
The first presentation [http://goo.gl/sBnjw3] covers the development of MoodleMobile over the past year and it’s future in terms of further development, features (offline) and contributors. Check out the MoodleMobile roadmap at https://tracker.moodle.org/browse/MOBILE.
The second presentation is MoodleMobile Plugin Development, which I think is just the beginning of some really cool feature development for Moodle as a mobile-based platform for learning. In the presentation it appears that Juan covered how to customize showing grades within activities of the app. Wish I could have been there.