StreetsAhead
Member
http://kotaku.com/child-predators-were-using-nintendos-swapnote-service-1459304126
Japanese articles:
http://headlines.yahoo.co.jp/hl?a=20131105-00001107-yom-soci
http://mainichi.jp/area/ibaraki/news/20131106ddlk08040158000c.html
Lock if old.
According to Yomiuri Online, two men have been arrested for performing "improper acts" in hotel rooms with the same 12 year-old girl on multiple occasions earlier this year. The girl met both men, aged 49 and 36, through her 3DS. Yomiuri Online doesn't specifically mention SwapNote. A Mainichi News report, however, does.
Mainichi reports that charges for child pornography have also been filed against another man, 44, who had allegedly two girls - then aged 11 to 12 - send nude photos through SwapNote, or "Itsu no Ma ni Koukan Nikki" (いつの間に交換日記 as it's called in Japan. The man has confessed to doing so.
In the above articles, both Yomiuri and Mainichi note that parents had initially turned off the 3DS's internet function, but the children had turned it back on.
Mainichi adds that there are other reports of the arrest - for statutory rape and indecency through compulsion - of predators apparently using the SwapNote function to prey on children.
Japanese articles:
http://headlines.yahoo.co.jp/hl?a=20131105-00001107-yom-soci
http://mainichi.jp/area/ibaraki/news/20131106ddlk08040158000c.html
Lock if old.
Looking at how many posters have no idea of how the Parental control work, it would be a good idea to add to the OP that the Parental Control is not a hidden obscure feature that you need to dig through menus and sub-menus to find. At THE VERY FIST TIME you switch the system on, it will go through explaining what the Parental Control is, how it works and it asks if you want to turn it on.
Basically every form of interaction can be blocked using the Parental Control. It is a very solid method and, as already posted, it will leave all these features or only the features you previously specified behind a password, that kind of works like the PIN of your credit card, with limited amount of tries.
Should a parent want to prevent their children to use any application that allows interaction with strangers, or Swap Note, which, per se, doesn't, they would be able to do so in a fairly straight forward manner. I believe Nintendo's Parental Control system alone prevents Nintendo to be blamed for what happened. The fact that they so quickly acted to shut the service down also shows their commitment in keeping their environment safe, which at this point, based on how Nintendo focus to appeal as a family brand, are almost entirely justified.