Steganography looked great in that hollywood movie Along Came a Spider with Morgan Freeman (or at least the 'screen friendly' version they portrayed) but a recent study of millions of graphics across USENET found zero steganographic images. Great theory, no examples found in the wild, other than in Hollywood scripts and some folk trading porn of the type not usually posted to the public Internet.
Steno principals are alive and well. Covert channel transmissions are alive and well. Both were used to bypass compartmentalization on a certain secure OS. If anyone needs to encode data in valid HTML to tunnel it through a firewall, it *will* be done. Several years ago, we had implementations of telnet over email, I am sure modifying it to do telnet over HTML would be a rather trivial task. Alex