July’s freely available Editorial in Nature Cell Biology explains the role of the preprint server — familiar to physicists, astronomers, astrophysicists and chemists — to biologists. Centre stage is given to Nature Precedings, and to how posting preprints and other documents on the site affects possible publication in Nature journals.
As described on Nautilus, Nature Precedings facilitates the sharing and discussion of prepublication data. It can host slide presentations, preprints, posters and stand-alone data. Postings are citable (DOIs) and attributable to an author. Although screened by in-house curators for scientific legitimacy (not novelty or quality), they are not peer reviewed, and, as a result, content can be posted in less than a day. The content carries a Creative Commons Attribution licence, which requires only proper citation.
The Nature journals, like many others, do not consider a posting on the site as a formal publication that would prevent consideration of a submitted manuscript for publication. But authors cannot post on Nature Precedings updated manuscript versions that evolve due to a journal’s editorial process.

Nature 448, xv; 19 July 2007