Aparently Final Fantasy 13 on 360 is only for Europe and North America, in Japan FF13 is PS3 exclusive.
Here is an excerpt from a live blog:
1:00 - Heidi Kemps asks when these will ship. Will PS3 and 360 ship at the same time? They say that they are just ready to star Xbox 360 development now. It will release in Japan first. Then, PS3 development/translation will begin, and Xbox 360 version should start about the same time. As for the US, the PS3 and 360 will release at the same time. Europe will also get a matched date, though it may not be the same time as the US date.
Kitase adds that they will try to get the Europe and US release dates as close as possible.
1:04- Shane from 1UP asks about Japan and the Xbox 360 version. He says that he hears that it is not coming to Japan. Hashimoto confirms that is is not coming out in Japan for the Xbox 360. As for Infinite Undiscovery, it is a 360 exclusive. Last Remnant will also be at first, but will probably be a PS3 title later.
1:07- Rob. Workman from GameDaily is asking about exclusive content for the different versions of FF 13. They have no intention to make different versions for the different platforms.
1:09 - A Japanese press member asks about the reasoning for the lack of an Xbox 360 Japanese release. Hashimoto says that he likes the spread of the Xbox 360 in Europe and the US, and they have not changed their mind on a Japanese version.