It's not unusual for services meant for innocent activities to end up being used for...not so innocent activities. Such was the case with Nintendo's Swapnote SpotPass feature, a messaging system that allowed images to be directly swapped with others. As can be imagined, the service was used to swap things Nintendo would prefer not to be part of its service, and after some time of deliberation, it was ultimately decided that the entire feature would be nixed.
Says Nintendo, it was brought to the company's attention that users have been posting friend codes on various online destinations and then using them to swap offensive materials with others. Nintendo says it investigated the misuse, attempting to figure out how to stop the problem without crimping the Swapnote feature as a whole. Such turned out to not be the case, however.
Ultimately, Nintendo decided to do away with SpotPass, doing so to help protect minors who also use the feature. The change has already taken place, likely taking those who used the service actively by surprise. There's no indication that it will be coming back at some point, though it is reasonable to think that, should Nintendo come up with a better solution, we may see a change in the future.
Said Nintendo: "We are very sorry for any inconvenience to the many consumers who have been using this service responsibly; however this decision was made considering the point that many minors also use this feature of Swapnote. Thank you for your understanding. Nintendo will continue to work to ensure more consumers are aware of our Parental Control features, which allow parents to manage their children’s experience on our systems."