I've been getting some very helpful advice and feedback on my efforts to start barefoot running. Thank you to everyone who has been advising me, and please continue.
Yesterday instead of running barefoot I went for a walk barefoot. I walked on both asphalt sidewalks and on a cinder track without too much discomfort. Much of what I've read encourages barefoot walking in between barefoot runs early in the transition from shod to unshod running. This allows you to continue to stimulate the development of your feet, and also allows for recovery from barefoot running.
I've got a long way to go before I'll be comfortable going barefoot. However, I continue to feel the changes in the sensitivity of my feet. I used have trouble just walking barefoot on my driveway, but now I can walk fairly comfortably for over half an hour on asphalt sidewalks and cinder tracks. I know it's not much, but I'm pretty happy about it.
For more on barefoot walking here are some resources: