I understand that just building a mobile application alone would not be of much importance but it would be an extra thing that I want to add apart from changing the wiki map-widget(which is one of the GSOC project idea).
Apart from using leaflet-apis for the map widget, the project would also aim at improving the authoring experience of the user. One method which I thought of was when user cilcks at the map, he would get the coordinates of the point(as a popup on the map where the user clicked) which the user could directly add or it can also be automated. This would improve the user interface to quite an extent. The same UI could be used for the mobile app.
One more feature that I was thinking of adding was text translation.Not all user have their native language as english so it would be useful to provide an option for translating text to some other language. This would even increase the usabilty of the maps and the user experience as it service the needs of the local people of various countries.For translation many apis are available and any one of them could be used.Though google-api is not free now but there are some methods through which it is possible to use them without paying.