Ethics Week Continues: The problems with kids these days (... as sources)

When is it OK to use young people as sources in a story, and when isn't it? The New York Times public editor tackled this question after one reporter queried 15 and 16year old students via Facebook for a story on what kind of person the famously media shy Cindy McCain is, and another reporter used a 12-year-old's account of witnessing alleged police brutality.