The Lightning network team has successfully completed a test involving the exchange of testnet bitcoin and testnet litecoin. While the cryptocurrencies changed owners, the transaction left no trace on either blockchain. The test has massive implications for users, as this technology will allow users to exchange coins much faster, while also enjoying increased privacy and lower fees.

In the future, this could allow peers on the Lightning network to function as mini-exchanges, competing with each other for the best exchange rates. The practical utility of cryptocurrencies could also be drastically improved by these instant exchanges, making it much easier for users to effectively spend coins on services that don't directly support them.

If you would like to learn more, Lightning Labs have released a video demonstrating their test.