There is a difference between EST and EDT. Many, if not most, people think that “standard” time is the time it is where you are. Or that it is the standard time for the time zone.
Right now, September 4, 2007, the “normal” time in New York is EDT (Eastern Daylight Time) not EST (Eastern Standard Time).
If you say today, that we have a meeting at 4:00 PM EST, that is a hour off from 4:00 PM in New York, because New York is on EDT right now.
Better to say 4:00 PM ET. That to me is Eastern Time. Standard or Daylight, whichever is in effect at the time.