Distance calculation

Hi all

Just playign about with a usful bolt on service for a site i am developing; where would i read up on how to calculate the best road distance between two given postcodes?

any ideas?

many thanks


By searching for something like postcode distance api

You can use the google API here: http://code.google.com/apis/maps/documentation/directions/

I plan on using this very soon as well because we need to use the distance calculations where we have multiple stops (way points)