Star Trek: TNG started in 1987 and they were carrying around iPad-esque devices in some episodes. I seem to remember Geordi Laforge often having one when interacting with the ship's engineering computer or whatever.

I'm mostly surprised by the fact that people are surprised by this video -- Fujitsu and others have been making tablets commercially for 15+ years. Alan Kay was talking about them in the 70s. The iPad was the right device at the right time (which is hugely important), but hardly a new idea in any way.

And in 1988 Tom Hanks, in the movie Big, described a interactive, digital comic book.