However I find I don't totally agree with some of the comments tending to tell us that we should not applaud good behavior or success. In thinking about this I think one could apply Herzberg's Two-Factor Theory.
I believe that applauding stories completed in a sprint review would fall in the Recognition factor, and is highly correlated to job satisfaction. While I believe that punishment for not completing a story (in whatever manner) would be found somewhere on the hygiene side of the chart, the side that leads to dissatisfaction.
To understand the difference image that your trash has not been taken out in a few weeks - does this make you dissatisfied, yes! But does the trash always being removed on schedule make you satisfied, no. Therefore the trash factor is a hygiene factor, and does not lead to satisfaction. Herzberg found that there is a dual continuum: a continuum from satisfaction to no-satisfaction with a separate continuum from no-dissatisfaction to dissatisfaction. Keep this in mind when you think of motivators, there may be a disconnect in the continuum you intuitively perceive.
Some interesting links on motivation.
A BBC video of Fred Herzberg describing the Two-Factor Theory. Or it may be a Doctor Who episode.
One More Time: How do you motivate employees?
David's notes on Drive by Dan Pink