A quick update for anyone who was having problems running my stochastic pruning demo on NVIDIA cards, I've updated the demo with a fix (I had forgotten to disable a vertex array).
While I was at it I added some grass:
The grass uses stochastic pruning but still generates a lot of geometry, it's just one grass tile flipped around and rendered multiple times. I wanted to see if it would be practical for games to render grass using pure geometry but really you'd need to be much more aggressive with the LOD (Update: apparently the same technique was used in Flower, see comments).
Kevin Boulanger has done some impressive real time grass rendering using 3 levels of detail with transitions. Cool stuff and quite practical by the looks of it.