I'm curious about seeing PTA's reaction also.
Original Screenplay that year was pretty stellar actually. That category included Anderson, Mike Leigh, and Charlie Kaufmann, but they went with Alan Ball. Alan Ball has more Oscars than Paul Thomas Anderson and Mike Leigh.
Anway, back to awards reactions. One that I loved was from a few years ago at the BAFTA's. Helena Bonham Carter won Supporting Actress for The King's Speech, and Miranda Richardon sure wasn't pleased. It's at about the :52 second point.