I'm not sure how these replies relate to the theft of shares from the link I posted. How does Ghash have anything to do with it (other than me throwing my speculative question related to their involvement)?
The 51% thing is a big deal but I wanted to talk about the fact that there seems to be a critical flaw with the way mining pools currently work that people can exploit(not >50% attacks, read my original link). The 200-300 BTC that the pool lost is a lot. What really makes me worry is that people can do it on p2pool and no one can stop them as far as I can tell. And we want people using p2pool but no one is going to want to if it's being exploited.
This is not a sensible attack on p2pool, the only way to do it would be to withhold a p2pool share that would currently solve a block, the withholding party would NOT get the block reward, but neither would the pool, on p2pool it would essentially just be throwing away the block solution and no one would benefit...