taxpayer - There's a big debate on this one. Under NIH rules, most research funded on your dime (and mine) must be freely available within a year of publication. On one side of the debate, open-access advocates (and others) say that's not fast enough; on the other side, publishers (and others) say that's too onerous. Within the last two years, competing bills have been introduced in Congress to either shorten the wait, or to scrap free access altogether. None have yet passed.
But to your point, there is no URL where you can freely read the entire text. You can, however, see the supplementary materials here: http://goo.gl/wfW8i.