Apparently Toei (was it Toei? whoever produced it) was told by a team of lawyers that Battle Royale could not be edited enough to be made fit for US release. This is the only reason it's never come out here.
I'm still waiting for someone to pick up Full Moon wo Sagashite. I know they're looking at it, just... not hard enough. :p
And I thought School Rumble was as good as licensed, but nobody's announcing. Lame.