Fark said it was broadcast exactly 30 years ago, but a search online indicates it was aired on January 21, 1978. Either way, it was momentous. Thing is, I remember watching it! I was pretty young in '78, but a HUGE science fiction fan (still am, baby, still am). The Saturn Awards were on TV, and I couldn't believe it; we had gone mainstream! I (vaguely) remember that they had an animated Pete's Dragon giving out an award; can any BABloggee confirm or deny that?
Anyway, Shatner came on, and even at the tender age of 14, I realized that we were seeing something that would be sung about for the ages.
The Shatner discusses this moment here.
And Wil, if you're reading this, I know how you feel about WFS. But c'mon. This is history.