According to the 360 flavoured version of Famitsu, Armored Core 4 will get its 360 release on the 22nd March next year. No details on any additional content as yet (bar the obvious inclusion of controller vibration and Xbox Live functionality) but a straight port of the PS3 version wouldn't be too shabby at all.
Having finished the singeplayer of the PS3 version, S Ranks, Arena and all, one small suggestion to those attentive ears at From Software would be the inclusion of an "easy" mode (in addition to the normal and hard that already exist). Otherwise many who haven't played the previous games may find the current difficulty erring on the side of fascistic.