The first draft of a formal spec of our mobile app has been published, for potential volunteer developers. See:
It basically describes the functionality as exactly as possible of the iPhone app, to make conversion to other platforms easier.
The document has not yet been fully checked, and a few missing API call examples (though they just mirror what's online) need to be added, but it is 99% done now.
Please let us have any comments on things that are not clear or where implementation would be ambiguous.
As stressed in the foreword, the spec is merely a template for creative work, not an exact blueprint for implementation, since other platforms will do things differently and the existing app needs changes anyway.