Here is the original photo to M's post. I would never use photos of other peoples kids anywhere. Never.
The decision to post photographs of kids on the internet, in my opinion, is to be made by the parents and the kid. Yes-I said the kid. I still remember the total embarrassment as a kid when my parents had friends and family over and presented a slide show—remember Kodak Carousels? I was 8 years old at the time and up flashed an image of a naked me in the bath tub with a soapy pointed hairdo. I was mortified—and to this day will never forgive my parents for that.
Happy responsible shooting & using!