According to a recent article in the Wall Street Journal,
"Today's home buyers aren't just looking for good schools and low crime rates when they evaluate a neighborhood, many brokers say. They're paying much more attention to what they can walk to." (emphasis added)
The growth of walkability as a desirable quality comes from homebuyers who want to avoid traffic as much as possible, and may also be looking forward to a day when gas prices get too high. Aging boomers buying homes to retire in and younger couples buying their first homes are both starting to look for the same easy proximity to town restaurants, shops, and activities.
This is why the towns I work in are so popular, and why I focus on the benefits of walkability when buying or selling homes. Though walkability depends on a number of factors - traffic patterns, topography - I have found that buyers are more and more looking to be within walking distance of things to do, and are willing to pay more for it.