STAR WARS
at the Academy Awards

Everyone knows that Star Wars, Empire Strikes Back, and Return of the Jedi scored big at the Academy Awards.  Star Wars was nominated for ten Oscars, and won six (plus a special achievement award for Ben Burtt):

Nominated:

Best Supporting Actor - Alec Guinness
Best Writing, Screenplay Written Directly for the Screen - George Lucas
Best Picture - Gary Kurtz
Best Director - George Lucas

Won:

Best Art Direction-Set Decoration - John Barry, Roger Christian, Leslie Dilley, Norman Reynolds
Best Costume Design - John Mollo
Best Effects, Visual Effects - Robert Blalack, John Dykstra, Richard Edlund, Grant McCune, John Stears
Best Film Editing - Richard Chew, Paul Hirsch, Marcia Lucas
Best Music, Original Score - John Williams (II)
Best Sound - Derek Ball , Don MacDougall, Bob Minkler, Ray West
Special Achievement Award (for sound effects) - Ben Burtt

I have never been able to find a copy of the 1978 (or 1977 - whatever you wish to call it) Academy Awards ceremony, so I can't really show you any pictures of it... but:  A while ago, abc.com put up two pictures from the show.  So based on those two pictures, it's my conclusion that C-3PO and Mark Hamill presented an award, but I don't know of any other characters appearing there.
But in any case, here are the pictures:

   

I have found several clips from the 1983 ceremonies, and will have some stuff posted eventually.