We did do an update on the Nature/asterisks following a request in twitter about the source of what I mentioned about changes in authorship policy in the journal (what’s in an asterisk). As I said, Nature refers you to the instructions to authors and to a web post for this matter. But, this is not clear. What is clear is what I have heard from authors which is that only three asterisks (joint first authors) and three corresponding authors are allowed. This is like an experiment, only time and use will make clear what this actually means.
One, two or ten, it does not matter. The point here is the one I made earlier, we should not let journals decide the way WE apportion the credits of OUR work. I am all for making clear the contributions of each author in a statement at the end. This is probably a better way to evaluate a piece of work. However while Impact Factor rules, while careers are being decided by first authorships in published work (particularly in journals like Nature), while we go through what is going to be a difficult transition, let us not forget that Science is down to the scientists and not to the journals we chose (and use) to publish our work.