The RouteTask can return turn-by-turn driving directions between points. To get the directions, set RouteParameters.ReturnDirections to true.

You can retrieve the directions using RouteResult.Directions. By iterating through this DirectionsFeatureSet, you can print the directions and access geometry segments for each step of the directions.

The ArcGIS JavaScript Extension for Microsoft Virtual Earth also allows you to draw the entire route at once through DirectionsFeatureSet.MergedGeometry. The following code shows how you might do this:

function responseHandler(response) {
  var results = response.Results[0];
  var directions = results.Directions;
  routeLayer.AddShape(directions.MergedGeometry);
}

If you decide to request directions by setting RouteParameters.ReturnDirections = true, you should not add the overhead of requesting routes (RouteParameters.ReturnRoutes) unless you need to access an attribute only included on the route. These attributes of the route could include the wait times and violation times associated with time window problems, or walk times.