Because it was designed to primarily be used via email, Posterous is a simple tool to start using. Anyone who can send an email can share thoughts, pictures and music with friends or the general internet public and will be completely at ease with this application. It doesn’t get any easier than that.
Kidding aside, the web transforms at a rapid pace. Daily even. Ten years ago, when everyone was tying up their phone line and using Netscape Navigator, could we really have seen how we would be sharing information the way we do today? Things have even changed greatly since the idea of blogging started to gain momentum.