Automated Transaction (AT) will allow atomic cross-chain trading (ACCT) with a second coin which is ACCT capable.

Translation:
AT allows to run small programs in block chain. Such a program can implement all functionality to exchange coins betwean two different blockchains (ACCT) without a third party like an exchange.
You not have to trust anyone. Your coins are always save.
https://en.bitcoin.it/wiki/Atomic_cross-chain_trading

There are many more use cases for AT. ACCT is only one of AT.
http://ciyam.org/at/