As a brazilian user I feel that the lack of multi-language support as a native feature of WordPress limit my ability to consolidate all my blogs into a single one. Presenting posts written into multiple languages makes for a confusing page. On the other hand, keeping separate blogs makes more difficult to build recognition.
My "requirements" are simple: I would like to be able to post a blog entry about (let's say) Scoble's or Godin's latest post, written in english, in such way they can eventually read; also, at the same time, I would like to have the same entry in portuguese so my readers would be more comfortable understanding what's being discussed. That's the value of this idea. Make it easier for different people to read and comment, but still into a single blog.