An Ethereum smart contract was published on GitHub by the group behind the project Altcoin Exchange, that allows direct exchange of Ethereum and Bitcoin without the need of a centralized exchange. I will spare the theory, because it's not the place for it here, but if you're interested you can read more about the approach in the group's initial repo, which made possible swaps between Decred and Bitcoin, Litecoin or Vertcoin.
If your first two words after reading this are ""Lightning Netwok" then you're right, the tech used by this group uses a similar approach, but, as far as I understand it's not Lightning Network.
The implications of such a tech are huge, because big centralized exchanges, like Poloniex or Bittrex, can see their (quite profitable, I'd say) business, hit by a new way of exchanging tokens directly between holders.
Please be aware that this tech, although proven to work, it's in a very early stage. Don't play with toys that you don't understand.
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