The basic idea is to feature one or more languages on your blog that you don't usually use. It could be that you usually write in a language that is not your native one, or that you do write in your native language but have other language skills. You could invite a guest blogger or bloggers to write in another language. It's up to you how you mark it!
Just sign up here, and don't forget to mark any posts or tweets with #babel14. For more information, or if you have questions, leave a comment on the blog or tweet me at @euonymblog
This year we are going global! As I am now in Australia, we're going to drop the "European" and just make it the Day of Multilingual Blogging.