If you are in need of determining the distance between two geo coordinates on blackberry, use the following piece of code.
private double difference( double currentLat, double currentLon, double startLat, double startLon )
Coordinates current = new Coordinates(currentLat, currentLon, 0);
Coordinates start = new Coordinates(startLat, startLon, 0);
float diffInMetres = current.distance(start);
return diffInMetres * 0.000621371192; //Convert into miles