. . .on homelessness and public libraries, at Alternet. In defence of library schools, I will say (contrary to the author's heading) that mine did included discussion of this topic, in the class that some accused of indoctrinating us in liberal ALA values.
My suburban system sees a little of this, though I think that the folks who come to my branch are only quasi-homeless. Perhaps because a touch of mental illness, one lives in a camper; and many young people live in group homes (for a variety of reasons). Capital City Library's Main sees a lot of this, of course.