CDC President William Norris planned to make PLATO a force in the
  computer world, but found marketing the system was not as easy as
  hoped. PLATO nevertheless built a strong following in certain markets, and
  the last production PLATO system did not shut down until 2006,
  *coincidentally* just a month after Norris died.

Emphasis mine. Is that some bitterness I detect? I guess it's a mark in Wikipedia's favor that things like that stand out, but still...