How do you establish "distance to work"? While searching for an apartments, I've always wished I could have a "heat-map" overlay of distance-to-work, taking in

How do you establish "distance to work"? While searching for an apartments, I've always wished I could have a "heat-map" overlay of distance-to-work, taking into account traffic at given commute hours. I suppose this should be possible nowadays with Google Maps' APIs.