[caymanjim]

Classified information, threats, bomb making instructions (borderline), categories of pornography, pirated media, libelous statements, trade secrets. Like I said, we may all agree that those things shouldn't be published--almost the entire world would--but some of them may be legal in some jurisdictions and not others, and there's a whole lot of grey area around the edges.

[javagram]

Classified information is regularly published in the news media, including through Apple News.

Bomb making instructions are available in books on the iTunes Store. https://itunes.apple.com/us/book/u-s-army-special-forces-gui...

In general you can legally publish pretty much anything in the USA besides child porn or copyright infringement, everywhere else has stricter laws though.