I have been asked what my next plans are, especially in comparison to Track'n Trail application. Well, right now I'm indeed working on implementing a graphical track presentation similar to Track'n Trail. If everything goes well, OSMTrack should become almost on a par in functionality with the Track'n Trail app soon (it will not support adding waypoints - they are of no use for the Open Street Map contributing; and sending tracks per email will possibly be added only with iPhone OS 3.0).
For the timing it is difficult to say right now. I have started OSMTrack with very simple architecture, so to say, let's try it and see what emerges out of it. Now I'm trying to develop a sustainable and extensible design, capable of doing much more then it does now. Also I 'm using OpenGL - technology which is new for me, I need some time to get familiarized with it, especially because OpenGL ES implementation of iPhone needs some special approaches different from OpenGL on desktop.
For the slippy map, this will be the next step. However, none of the existing frameworks - route-me, CloudMade iPhone Maps Library and a new iPhone OS maps framework suffice my requirements. In fact, I've even created a sample application branch using route-me framework, but it was slow and had bad GPS reception (it seems GPS reception quality depends on how busy the iPhone is). My requirements are simple - tracking shall work also in places where there is no network coverage. For this I need maps being rendered from local vector data (of course, it is also possible to use pre-cached bitmaps, but read further). This is why I'm doing it with OpenGL. Maps will be done in multiple steps, starting with street map only - no colorful areas like forests, lakes, etc. (currently OpenGL ES implementation on iPhone doesn't provide GL Utility library helping to draw arbitrary poligons, not just triangles).
And the final step on the OSMTrack roadmap is map editing. At least for the map editing I will definitely need local raw vector maps. I have not even started thinking on how it may look like, but still I'm trying to design tracking functionality so generic that it shouldn't require changes even when map editing is implemented. This is the difficulty.