A new Distance Matrix service has been added to the Google Maps API.
The Distance Matrix service allows you to display the travel distances and times between a number of locations. For example, the image below shows the walking times between different London Underground stations and important landmarks.
This example Google Map uses the Distance Matrix service to show the driving distances from Edinburgh to Stockholm and Prague and from Greenwich London to Stockholm and Prague.
For more information see the Maps API services documentation, and the Distance Matrix API web service documentation.
Via: Google Geo Developers Blog