Development Hell — There is a patch for the Xbox 360 version of DaiOuJou that fixes the numerous bugs in the game (see Porting Disaster). It took about two years since the game was released to make; by the time it was out the sequel DaiFukkatsu was already ported.
Keep Circulating the Tapes; DoDonPachi Campaign Version, a single board of which was distributed, and to a contest winner. As such, this version is not available in MAME, and if the board becomes damaged beyond repair, this piece of history (and arrange mode of DoDonPachi) is gone. Forever.
The first game has a proper US release, and the second has an "International" release. And that's only for arcades; none of the console releases have made their way outside of Japan.
Rising Star is set to finally end this trend with a European release of DaiFukkatsu (under the English title used for the iPhone game) in November 2011. However, North America shows no sign of getting it.
Rising Star has announced that the European release will be compatible with US-NTSC consoles. So North America does get it... if they're willing to import. However, an EU Xbox Live account is needed for the V1.5 and Black Label DLC's. And the Black Label Arrange mode (aka "Ketsuipachi") is not available outside of Japan.
The iOS ports are downloadable in America, however.
The retail version of DaiFukkatsu Black Label. Although the DLC version of Black Label is available in the PAL version, which has no region lockout, it does not have the the Ketsuicrossover arrange mode that the retail version has.
Irony: The Ketsui arrange mode's soundtrack was arranged by Jake Kaufman, an American composer.
SaiDaiOuJou, though at the least it is region-free.