Robert Cringely has another good article on PowerPoint abuse, making the observation that because of the manner in which Powerpoint (intended as a visual aid, not as a means of communication in itself) is misused to become the message instead of aiding the message, with the resulting loss of information because you can only fit so much on a Powerpoint slide, we have largely ceased to communicate without realizing it. Giving a Powerpoint presentation, we are not speaking, and sitting in the meeting room staring at the presentation, we are not listening. Between the presenter relying on the slides to serve in place of data, and the audience expecting to derive insight from the slides, little communication is occurring.
A picture may be worth a thousand words, but a PowerPoint slide is not, and when we rely on PowerPoint slides instead of actual communication, the author comes out of the meeting room convinced he conveyed his message, and the audience leave convinced that they understood what he meant; and both are wrong.