Google Directions adds real Traffic Times
Google Maps Directions adds real Traffic/Journey Times
Very simple but very useful
Going to JFK to New York (Google's centre point for New York) or vice versa in this example - waiting 10 minutes between requests shows two different sets of traffic and therefore adjusts the approximate time for the journey.
Knowing the 'appendence' of each segment of line (road in this case) and the distance is therfore easy to work out the time it will take to cover that segment, join them up and you get an ETA of the journey.
Official Post from the Google Lat/Long Blog
Next transitional times - incorporating walking time, trains, train stops, buses, trams as well as Traffic?
Geocoding Expands India, Hong Kong, Taiwan, Singapore, or Ireland (Via the MapRoom)
Official Post by Pamela Fox