On the Atari Forums there is word on beta applications for the expansion that has been announced for Act of War.

Atari and Eugen Systems are please to announce a closed public beta test for the upcoming Act of War: High Treason expansion. The highlight of this first expansion pack for Act of War: Direct Action is a major new feature – it's the first RTS game ever to feature modern naval combat! In addition, several major and minor additions and adjustments have been made to improve and simplify the experience of the original game, such as new units, upgrades, and streamlined interface mechanics.