In Game 5 of the first-round playoff series between the Memphis Grizzlies and the Los Angeles Clippers, Tony Allen's layup attempt stopped on the back of the rim:
This is ruled a jump ball.
Meanwhile, in Game 4 of the series between the Houston Rockets and the Oklahoma City Thunder, Serge Ibaka's potential game-tying layup at the buzzer came up just short:
What would have happened if Ibaka's layup had stopped on the rim? There couldn't be a jump ball after the buzzer has sounded, could there? It seems impractical to wait longer and see if the ball would eventually drop through the hoop. Does that mean it would simply be ruled a missed shot and the game would end?