SEGA has recently launched it's own US website for Armored Core 4, which is practically a mirror of FROM Software's Japanese page.  The fact that the pages are so strikingly similar suggests that the two companies are working together much more closely than FROM Software worked with previous publisher, Agetec.  The website has information about the game, the storyline premise, the corporations, the gameplay, and of course, the ACs.  Most importantly, the site pins the release date for both the PS3 and XBOX360 versions of the game to March 2007, only a month from now.  More news on this as it becomes available.

 SEGA's new page can be found here: http://www.sega.com/gamesite/armoredcore4/index.html