I'm just going to put this out here, because I called this when Dharma started proselytizing. I was told this wasn't possible and that I was stupid for having a concern about this.
http://bitcoinmagazine.com/9402/mining- ... 1391879410One of the key requirements for the Bitcoin network to be secure is that mining, the distributed process in which the network processes and secures transactions, must be decentralized; that is to say, there should be no single individual or entity with more than 50% of the computing power of the entire network. If the condition is not met, then Bitcoin essentially collapses into a less efficient model of a centralized database, where the majority shareholder can unilaterally block and even reverse transactions at will. Most of the time in Bitcoin’s history, this condition has been met; although miners do organize themselves into centralized groups known as pools, there have been a wide array of pools to choose from, and usually no single one has had more than a quarter of the network’s power. Over the past few months, however, a new mining pool has emerged that has come to be a serious threat to this status quo: GHASH.io. The mining pool’s hashpower first increased to 30%, then 40%, and now the situation has hit a peak where the pool controls an impressive 45% of the network – just shy of the 50% needed for Bitcoin to turn into a system of de-facto centralized trust.
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The BitCoin community is losing their minds over this. They have started encouraging people not to join this pool because of how close they are to the 51%. That's right: the only way this currency can continue to function is if more people deliberately adopt market inefficiencies