The best way I've seen this done is carrot and stick combined. When I worked with MySpace/NewsCorp (for all my sins) one of the things I was most encouraged by was their anual review...
EVERYONE in the company was given an anual performance review by their manager with a final mark out of 5.
Then out of no where it was simply announced that EVERYONE who got 1 or 2 out of 5 was fired. No one knew that was going to happen but it was simple + effective.
Low performers, slackers, idiots and the like were immediately expelled from the company. Everyone who was pushing like crazy was inspired to go on and do more with a revitalized team. Anyone who was thinking about slacking was thus incentivized not to going forward. People who knew they were out of their depth and might get a 1 or 2 next time started looking for a different job. It was a harsh yet thoroughly effective move.
That, combined with salary raises makes for effective, rewarded teams IMHO.