The short version, for those who don't want to click the link, is that schools are increasingly choosing to lock disruptive children --- often children who have autism or other developmental disabilities --- in small, isolated "time-out rooms," sometimes for hours at a time.
There's a quote, midway through the article, from Vanderbilt University's Stephen Camarata, that I think is right on the money:
I believe [the use of time-out rooms by schools is] because classrooms are much less flexible, with more focus on compliance.
That's probably the worst possible outcome of mainstreaming: that the special-needs kids' special needs are completely forgotten, and they are either ignored (if they're quiet) or punished (if they're not quiet).
When I think about myself as a child (and, really, even up into young adulthood), I see someone who takes what she is told absolutely literally, and who has a hard time recognizing the signs of physical distress. While a normal child, if she were getting hungry, dehydrated, feeling faint or having to go to the bathroom, would raise a fuss or decide to leave the room anyway to take care of herself, I would not have had the maturity or the self-awareness to do that.
I don't think teachers always realize just how vulnerable their autistic students are.