New to BTC and NMC, I've read the wiki and FAQs, but still have a few questions

[Senjougahara]

1. What prevents some body from two timing the system? i.e. signing up for every available pooled mining group, and sending the data to all of them? I assume that the worker system is supposed to prevent this, but don't understand how it does. As in, why can't someone create a hack to check for solutions, and save those instead of sharing them?

2. From what I've read on these forums, Slush's Pool doesn't share the transaction fees. Will this change when we get to block number 210,000? If not, I'd think that the pool in it's current state isn't suited for long term.

Thanks, the model of bitcoin seems pretty cool. I'm pretty interested to see how digital currencies work as the internet age develops. Hopefully we won't find that P = NP.

[scintill]

1. What prevents some body from two timing the system? i.e. signing up for every available pooled mining group, and sending the data to all of them? I assume that the worker system is supposed to prevent this, but don't understand how it does. As in, why can't someone create a hack to check for solutions, and save those instead of sharing them?

The data that is being hashed by the miners is different for each pool, because each pool sets the payout address for the block reward to their own address.  So, a solution to a block at one pool isn't a solution to the block at a another pool.

Also, since the payout address is part of the block, this is why you can't "steal" the reward from the pool -- if you wanted to change the address to your own, the solution would no longer be valid.

[odolvlobo]

Miners choose a pool based on how much money they will make from the pool, and pools compete for miners. When transaction fees become a significant part of the reward, a pool that does not pay out transaction fees will lose miners to the pools that do. Of course, pools might not pay out transaction fees directly, they might lower their cut by the average transaction fee amount instead.