Posting naughty drawings for the public to see will not be tolerated.
In a recent interview, Satoru Iwata has detailed Nintendo's proposed method of how their Miiverse public posting content filtering will work.
Firstly, content will be filtered for inappropriate words through the use of a software program. Secondly, Nintendo plans to hire people to manually check posts before they are made live. However this method requires more time, at the moment a delay of at least thirty minutes is expected. The last line of defence against any questionable content, is that the users will have the ability to flag content that is offensive. However, it was stated that this method isn't as ideal because the user has already seen the content.
It appears that these measures with content filtering only apply to the main public home screen and other public posts within games, and not messages between friends.