You could use it for pinyin annotations too, or really any combination of scripts.

睾丸 こ がんに豚ぶたの糞くそ

猪蛋蛋上的粪便 Zhū dàn dàn shàng de fèn biàn

фекалииfekalii наna свиныхsvinykh яйцах yaytsakh

People were just talking about this in a thread earlier but I can't find it anymore. Figured this would be a good place for it.

Check out the source code of this post. It actually looks for space characters after the pipe symbol and uses that to group the furigana. It's actually easiest to use for Chinese, Japanese is a bit more work, and alphabetical scripts are pretty time consuming, because you have to mark up each word with brackets and pipes, spaces don't cut it.