Converts KML shapefile syntax into a Google Maps Polyline. It is rather ironic this is not built into Gmaps since it is Google's spec.

convertKMLtoGoogleMapsPolyLine.js

function getPolylines(geometry, style) {
    // Parse Geometry
    var kmlstring = geometry.toString();
    kmlstring = kmlstring.substr(40);
    kmlstring = kmlstring.substr(0, kmlstring.length - 43);

    var linestrings = kmlstring.split("</coordinates></LineString><LineString><coordinates>");

    // Set polylines
    var polylines = [];
    for (var i in linestrings) {
        var linepoints = linestrings[i].split(",0 ");
        var routeLine = createLine(linepoints, style.color, style.stroke, style.opacity, style.zIndex);
        polylines.push(routeLine);
    }
    return polylines;
};


function createLine(linepoints, style, stroke, opacity, zIndex) {
    var coordArray = [];

    for (var i in linepoints) {
        var coord = linepoints[i].split(",");
        var lat = coord[1];
        var lng = coord[0];
        var lineCoord = new google.maps.LatLng(lat, lng);
        coordArray.push(lineCoord);
    }

    var routeLine = new google.maps.Polyline({
        path: coordArray,
        strokeColor: style,
        strokeOpacity: opacity,
        strokeWeight: stroke,
        zIndex: zIndex
    });

    return routeLine;
}