On the over-use of HIGH PRIORITY in email today
For those of you who may not recall, the Priority: header was originally designed for mail servers to properly prioritize the routing of messages in the days when broadband meant 256K (wow!), and it was customary to move batches of mail from one place to another at different times, such that a notice about a meeting taking place next month would be assigned a lower priority than, say, a message concerning the temperature in the boiler room (reference to nuclear reactors specifically avoided, as the situation in Japan is non-trivial and surely not humorous - as several comedians have recently discovered). The Priority: header is/was analogous to the X.400 priority field. (For references, see RFC 2076, 2156, et. seq.)
Along came our good friends in Redmond, who decided that an X-MSMail-Priority: header was important, too, so that (idiot) users could jump up and down and yell "FIRE!" in the movie theaters...er...so that Outlook (Outbreak) users could prioritize their own messages (and of course, an emergency on the part of a client does not necessarily constitute an emergency for me).