Displaying TEI footnotes

[rsimon]

Via CETEIcean, footnotes represented as a element just appear inline in the text. Should/could we find a (reasonably simple...) solution that would make them appear as actual footnotes? E.g. at the end of the document (hyperlinked), or as a popup? I assume that at least the latter could be made to work in a CSS-only way. (CC-ing @hcayless for info.)