The Cost of Knowledge: Researchers taking a stand against Elsevier. 15 years ago
Several Journals (such as PNAS) now provide the option for authors to make their papers "open access". Usually by paying an extra fee (around $1,500 for PNAS). Some authors do this since it can increase their visibility.
In other cases, it is a condition of funding that that the paper eventually be freely available (sometimes with an embargo of about a year).
In all, I think the open access model will become more widely accepted, with the exception, maybe, of papers published in the top journals, such as Nature or Science.