I'm fascinated by some of the things you can do with technology. In writing. I think we need to stay up on the latest technologies so we don't make dumb mistakes in our plotting. There are all kinds of communication devices as well as ways of hiding information in today's world.
Steganography is the art/science of creating hidden messages so that only the sender and the recipient can read the message. A recent episode of the TV series Bones featured steganography as a plot device.
Actually, this isn't a modern day invention. The word is from the Greek meaning concealed writing, and the first recorded use of the word was by Johannes Trithemius in his Steganographia in 1499. His work was a treatise on cryptography and steganography and was disguised as a book on magic.
The way it works is that the secret messages appear to be something else entirely, i.e., pictures, articles, or some other mundane text. Old school ways were to use invisible ink between the visible lines of a private letter. If you were a kid into reading kid mysteries, you know you dip a pen in lemon juice and writ on paper. You can't see the writing until you apply heat to the page. That was similar to the principle used in the movie National Treasure where a treasure map was on the back of the Declaration of Independence.
If that gets your imagination working and you want to learn more about steganography, watch the lecture. It's fascinating.
A writer must write for the culture in which he/she lives. Even the world we inhabited 10 years ago is far different from today.