A location library for Titanium. I put this in a /Resources/lib directory

location.js

/** 
 * Computes the distance in miles between two sets of coordinates.
 * 
 * @param   object  from    object containing longitude and latitude members
 * @param   object  to      object containing longitude and latitude members
 * @return  number
 */
exports.distance = function( from, to ) {
    // approx. dist in miles, nothern hemisphere
    // http://www.meridianworlddata.com/Distance-Calculation.asp
    try {
        return Math.sqrt( Math.pow( 69.1 * ( to.latitude - from.latitude ), 2 ) + Math.pow( 53 * ( to.longitude - from.longitude ), 2 ) );
    }
    catch( e ) {
        throw( e );
    }
};

/** 
 * Calculates the region for a mapView so that all points are dislayed.
 * 
 * @param   array   points  An array of objects with long/lat properties.
 *                          Essentially, stripped down annotation objects.
 * @return  object  a region object
 */
exports.region = function( points ) {
    var region = {}; 
    var delta  = 0.02;
    var minLat = points[0].latitude, 
        maxLat = points[0].latitude, 
        minLon = points[0].longitude, 
        maxLon = points[0].longitude;
        
    for( var i = 0; i < points.length - 1; i++ ) {
        minLat = Math.min( points[i + 1].latitude, minLat );
        maxLat = Math.max( points[i + 1].latitude, maxLat );
        minLon = Math.min( points[i + 1].longitude, minLon );
        maxLon = Math.max( points[i + 1].longitude, maxLon );
    }
    
    // Define the zoom level
    var deltaLat = maxLat - minLat;
    var deltaLon = maxLon - minLon;
    delta = Math.max( deltaLat, deltaLon ) * 0.25;
    
    
    region.latitude  = maxLat - parseFloat( ( maxLat - minLat ) / 2 );
    region.longitude = maxLon - parseFloat( ( maxLon - minLon ) / 2 );
    region.latitudeDelta = region.longitudeDelta = delta;

    return region;
};