A new feature has been added to the unofficial version of gvSIG Mobile for Openmoko. Simply by providing a shapefile describing the POIs (actually the polygon type is recommended) and a few JPG pictures, the application will show a dialog every 20 seconds with a description of a nearby POI and its relative position (in front of you, behind you, to your right, to your left or you are inside). The user only has to push the image to close the dialog and decide where he wants to go.
This is the tiny polygon shapefile I used in my test:
And here is the demonstration:
This feature will be available in the upcoming 0.1.4 version.