According to correspondence from an Elsevier correspondent to Rosie Redfield, Elsevier is charging authors a rather substantial amount ($3,000 per article), because they do not plan to charge subscribers for author-sponsored content.
Has any librarian heard the other side - subscription fees going down because of author-sponsored content?
Authors: if you're going to pay for open access, make sure you are getting open access! There is a lot more to OA than just free access from one website. Here is the definition of OA, from the Budapest Open Access Initiative:
By "open access" to this literature, we mean its free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited.