One thought about the ypool mining software.
If I understood the conecept correctly, you accept chains below the current difficulty as shares. If a chain, which meets the current difficulty is found by one of the miners, the pool found a block.
How do you protect the pool of the following scenario:
One creates a fork of the orignal sources, that does the following: If the miner finds a chain with lower difficulty it submits a share to the pool. If it in fact finds a proper chain for a block it marks it as solo mined. I'm not a programmer but I assume it whould not be a big hack to implement that.
Sorry for the bad English but I hope it´s understandable what I want to say.