Times sure are changing for SNK and their once strong relationship with publisher Ignition. It once was a staple to see an SNK game published outside of America by Ignition software but if recent ESRB listings are correct, it looks like that might no longer be the case.
The new publisher in America looks to be none other than Atlus themselves as the ESRB listing for Metal Slug XX for the PSP shows them as the publisher for the game. Atlus USA has been pretty active of late picking up games and bringing them stateside and now it looks to be adding another to its list. I guess it does not matter who publishes it, we should just be thankful this classic game is coming stateside.