It may be illegal, but it's impossible to prevent. It forever will be and always has been difficult, but not impossible, to publish to the Internet in a manner that is approaching pure anonymity. The reason people will wonder if it is legal is because of the negative connotations that anonymity itself brings (ie. the mindset that people with something to hide are usually doing something wrong). Nations may try to outlaw such a thing, however, it will forever be a stop-gap measure, doomed to perpetual failure. The Internet knows no legal jurisdictions. The very idea that posting something 100% anonymously is illegal is oxymoronic anyway. How can you charge someone with posting something anonymously on the Internet if you were able to figure out who they were in order to charge them? Obviously their method wasn't very anonymous.