The Miami defender isn't even looking back for the ball. He face is buried in the OSU players chest with the ball in the air. Clearly pass interference
Here is a thorough analysis of the play.
http://www.youtube.com/watch?v=NFpTkYMLzdc&feature=fvw
Ball hit Gamble's hands clearly BEFORE Sharp hit him. Check out the various slow motion replays.
In the words of annoucer (and Hall of Fame QB) Dan Fouts:
BAD CALL!
The 2002 National Championship Ohio State has is TAINTED!