The game has been recently rewritten and because of this, only the single-player mode is active for now but this should change really soon! Please note that I didn't play it for too long so I'm not sure how complete the single-player mode is. However, for a pre-alpha version, the 0 A.D. looks great so far!
Screenshots can be found @ http://wildfiregames.com/0ad/album_cat.php?cat_id=49
And speaking of Wildfire, there is currently a campaign called the Humble Indie Bundle - a pay-what-you-want (any price whatsoever), DRM-free bundle of 5 great indie games worth US$80. You can also set how much to give to the developers and how much to charities. And an interesting fact: so far the Linux users paid the most for the indie games.