Google Maps has introduced its walking directions--currently in Beta. When you select directions you are given the choice in a drop-down menu of "By car" or "Walking."
Google has taken on a gargantuan task, in my opinion. The enormous number of shortcuts available to savvy walkers is virtually infinite: plazas, alleys, cut-through buildings, pathways, etc. Then there is the opposite problem--places where a map indicates a street or road, but that would be either impossible or unsafe to walk. How they will sort that all out is going to be interesting to watch.
For instance, I tested out the directions from my house to the Ballston Mall (I live just off I-66 about a mile east of the East Falls Church metro). The shortest and most pleasant way for me to get there on foot (or bike) is on the Custis trail, but Google Maps doesn't know the Custis Trail exists, so it routed me along Washington Blvd., adding about 1/2 mile to the distance. Maps.ask.com, which also provides walking directions also did not indicate the trail.
I think this is a great idea, though, and I hope Google and ask.com are successful at making this service accurate and useful. Try it out for yourself.
Steve Offutt just purchased a new pair of sandals for walking.