The site is very nicely implemented, with all the Web2.0 features we have come to expect from Nature Publishing Group, including tagging (documents and people), voting for articles, and open discussion on articles, etc.
Perhaps not surprisingly, by far the largest single subject category is Bioinformatics, with 20 documents. Biotechnology, Evolution & Ecology, and Molecular Cell Biology each have 9, while other topics have only a couple of documents. It will be interesting to see whether this distribution just reflects the make-up of the beta testers, or whether it will hold as the site attracts more submissions.
The list of partners has also been released: the British Library, the European Bioinformatics Institute, Science Commons, and the Wellcome Trust. Nature hopes the stature of the partners will allay fears about Nature’s plans for possible future control of the content.
The site differs from some of the earlier preprint sites (like arXiv in physics) in that it accepts powerpoint presentations as well as journal article preprints, e.g. this interesting presentation: Open Notebook Science Using Blogs and Wikis.
UPDATE/CORRECTION: There’s a mistake in these figures, see here for the correction