[TTPrograms]

I don't think that's quite right. Arxiv is a third party for academics to publish paper to get informal peer review outside of journals. My guess is that any edits made based on feedback from Nature's author network as well as the actual paper in the Nature format are under Nature's copyright.

But yes, my understanding is that anybody with institution access to Nature can now share a link to the Nature publication.

[privong]

> My guess is that any edits made based on feedback from Nature's author network as well as the actual paper in the Nature format are under Nature's copyright.

Half correct. The authors retain copyright for changes due to feedback (peer review), as the authors themselves would have modified the paper to address any feedback. You are correct that the actual paper in the Nature formatting (and possibly associated copy-editing) are under Nature's copyright.

[jsprogrammer]

Arxiv shows that the most recent revision of their document was published on January 20, 2015 (less than three weeks ago).

I suppose it is possible that Nature's version is substantially different, but if that were the case it would cast a huge shadow of doubt over Nature's editorial process, as well as the claims made in the paper itself.

[TTPrograms]

The differences are likely a few small sentence additions, citations and comparisons to other work. I think the results would remain unaltered.

[montecarl]

Peer review and getting an article published takes at least a month if not half a year or longer. The preprint on Arxiv is most likely the final version of the paper they submitted for publication post peer review.