Sorry Don, I somehow missed the Case study page when I read the presentation.

Did you have any template support for checking whether a version in another language is available or not? How would I implement that?

I don't see many language switches on Greenpeace site; it looks like there are just completely different sites for each language. I have "different languages, identical content" approach and put language switch on every page, not just a link to the root of the site in another language. The multilinguality is handled on a per-page basis. Every page needs to know in what languages it is available, and also be able to ask the same question about any other page in the system.