Meanwhile more projects are using QMapControl. Most recently I received a mail from Lorenzo wherein he informed me he uses QMapControl to display wireless networks within a map (http://code.google.com/p/qnetaddressbook/)
Another project (which uses QMapControl the way it originally was developed for) is Open Citymap (http://code.google.com/p/opencitymap/) which provides a map client for Qtopia compatible devices.
With the method "enablePersistentCache()" of the MapControl class you can enable the persistant storage of map tiles over application restarts. By default the tiles are stored in the subdirectory "QMapControl.cache" within the user's home directory. This can be changed by giving a QDir.
The second new method is "showScale(bool)", which displays a distance-scale within the widget.
The OpenStreetMap editor Merkaartor (http://wiki.openstreetmap.org/index.php/Merkaartor) is using QMapControl to display maps in the editor view.
They evolved QMapControl, to provide persistent caching of map tiles. This new feature will be merged soon into QMapControl´s codebase.