Lately I've been lucky enough to find time in the mountains with only my Vibram Five Fingers between me and the mountain below. Taking on normal mountain hikes using your feet the way they were designed really changes things. My feet are finally tough enough to handle hours of rough terrain without any of the 'support' my normal shoes were offering me. In the same sense as a cast can be supportive. Though you can expect the same muscle atrophy that results from any cast.
The barefoot culture seems to be enlightened to the notion that our feet really do have a function other than something to fasten a tight fitting highly padded wedge shaped running apparatus to.
A great site I was recently turned on to, birthdayshoes.com, shows all sorts of folks out enjoying their feet and learning how to walk again. They've also posted a picture of me!