adamr: The Stealth program is more than just steganography, which is indeed a well-known technique implemented across many platforms. I think what the article is referring to as unique are the arbitrary 'containers' Dr Queen talks about, which can only be detected by supplying the valid decryption key for each one, thus allowing other private 'containers' to remain undiscovered as, without the key, you can't prove they even exist.
In case anyone starts spouting the rubbish about "those with nothing to hide" etc. etc., some people on this platform genuinely do need to use programs like GnuPG and Stealth as a matter of utmost importance, for example I have a friend whose family is based in a country with a repressive government, and they sometimes need to hide their day-to-day communications or risk persecution.
VinceH: it's ok, they'd release you after a few weeks by mistake and forget where they left you