The act or acts of using public information networks such as newscasts or newspapers in a misleading, devious, or mischievous way, to disperse a hidden propagandic message that seems plausible to the population.
Coined by Bob Corduroy on Comedy Central’s “The Daily Show”, Wednesday 17th of March 2004.
The word has gotten mainstream acceptance with its use in an Op-Ed column by Frank Rich of the New York Times.
UPDATE: Geoff Nunberg has found older citations:
As it happens, “infoganda” has been around for a while — it first appeared in the press during the Gulf War of 1991 as a name for the reports and footage that the Pentagon was furnishing to journalists.1 But the word may very well have been independently coined on several occasions.