A port of Raiden IV for the Xbox 360 is apparently in alpha stage and is scheduled to be released in the US at some unspecified point in the distant future. This news comes from an interview with one of UFO Interactive's managers recently conducted by Team Fremont. (And don't forget, UFO is also bringing to the US the PS2 port of Raiden III later this month.)
This is all very surprising, especially considering that it's going to be a while before Raiden IV is even released in Japanese arcades (it's currently slated for July). Moreover, no news of a Japanese 360 port has emerged through any of the usual sources. What has me worried the most is that UFO is considering releasing this on XBLA, which could very well mean a shoddy port in unsuitable resolution and with no option for tate. On the other hand, even if this is a regular disc release it could turn out ugly. By Royal decree all Xbox 360 games have to be 720p minimum and Raiden IV is a 640x480 game -- which is not even a widescreen resolution. G.rev faced the same problem when porting Senko no Ronde, but then again their game was in yoko so things were much simpler. It will be interesting to see how this gets handled.