Contrary to what seems to be a kind of it hasn't happened yet so it won't happen consensus voiced here, I think reflection about language issues in WP is long overdue. Recent WP development has been all about the shiny bits - multimedia (still clunky), the fantastic things for theme developers... but nothing about what should be basic core functionality. Language attributes is a start, but I think there should be some sort of thinking about how (even if the nuts and bolts are done through a plugin) multilingual posts could/should be implemented. Almost all the plugins I've looked at or tried out have tags within the post that wrap the content for each language - I still use one developed by Jennifer Hodgson years ago that works this way - a language attribute would be useless in this case as the post contains both (or more) languages. With a language attribute metadata the logic would be a each language version of a post would be a post in itself (in the database) which would then be linked in some way (so that they could be retrieved for comparison and editing and selected at the front end). I don't think you can introduce post_language() without thinking through to end of the process. But it is essential that it be done !