As AOL pursues its patent on instant messaging, people all over the Net are assembling examples of "prior art" -- instant-messaging-like systems that long predated AOL's. Rafe Colburn recalls one from a company he once worked for. Brian Dear writes in to point out that the PLATO system had IM functionality back in 1973. [Scott Rosenberg's Links & Comment] I remember using PLATO at Indiana University in 1979 or 1980. Black screen with orange text...