Slang for an obsolete form of 2D-approximating rectangular carbohydrate-based information transport object. A.K.A. "Paper".
Seen on a sign: You can't grep dead trees
On the other hand, you can read dead trees while the plane is taking off or landing. (It's also a lot easier to put sticky-notes on dead trees.)
Airline magazines are often where executives first encounter some whiz-bang IT fad and "want it badly". (Related contrast: ProgrammersRefuseToUseStateOfTheArt)
A dead tree is often the SimplestThingThatCouldPossiblyWork.
When computer monitors can do 1200 dpi, then you can have my DeadTrees. Not before.
See also EndOfEmploymentSingularity