Two Google Map mashups in two days!
This one's by Google themselves.
Basically in North America, if you go to Google Maps and put in two locations you've now got the options for driving directions or walking directions!
Google states that their walking directions will try to be direct, flat, and if available, uses pedestrian walkways.
Of course you'd better hope that Mr. T.'s not driving around your neighbourhood as evidenced in this fabulous ad for Snickers.