Fans of the Terminator mythology know that today -- April 19, 2011 -- is the day the eventually-self-aware computer system Skynet goes online. Well, sort of. Time travel is complicated. ---
Here's one version of events, according to Terminator 2: Judgment Day: Skynet went online August 4, 1997, and became self-aware on August 29. Long story short, humanity is toast.
But of course, there's plenty of fussing with the time-space continuum over the course of four films and a television series. And it is in the short-lived Fox show Terminator: The Sarah Connor Chronicles that the revised Skynet activation date was identified as April 19, 2011. So either we've been living with this scary entity for nearly 14 years now, or the end is near. I, for one, welcome our new computer overlords.