I haven't read the CSS3 Ruby drafts, so I don't have any comments. But I did find some interesting examples:
Footnote Ruby and Underlined Ruby - Footnotes in Japanese texts are typically written in between lines, like ruby. You can see this in the third line.
Underlined text is top left. Note that the underline is along the "before" edge, and also that it's between the ruby and the main text.
Kanji Ruby 1 - Ruby is usually a phoenetic expansion of the associated word. Here, the ruby text is kanji (Han ideographs). Note the parentheses.