Someone else had the same idea, for as of today, Google Maps now offers walking directions. The feature is still in beta: it does not incorporate pedestrian-only off-road paths, and the option to toggle from driving directions to walking will not appear for routes over 6.2 miles. You don't need to be plotting a walk across America to find that distance limiting many leisure walks easily extend beyond that length. But for the around-town needs the directions are intended to fulfill, it's a great first start, and coincidentally estimates the travel time at my own walking speed average of 3 MPH.
If you find this feature useful, you may also be interested in (or already know about) Walk Score, which determines the "walkability" of any neighborhood based on how much you can do within the address you input. This means that downtown Boston or New York City will have a high walkability score, while almost anywhere in the expansive landscapes of Kansas or Montana will not, making it a tool more valuable for living with limited gasoline consumption than for finding a leisurely Sunday stroll.
I'm hoping the webmaster of Pedestrianfriendly.com will be along shortly to comment on these intersections of technology and simplicity. In the meantime, enjoy these new ways to reintroduce yourself to your neighborhoods.