Thanks to an alert Facebook friend, I read "What's the deal JSTOR?" by Meredith Farkas on her blog, "Information Wants to be Free." I had noticed some changes in JSTOR's look and a new box to check on their search page: "Include links to external content". Ms. Farkas explained it all. Not every library subscribes to the complete range of publications offered by JSTOR. Used to be that the others just weren't shown if you only subscribed to a few. Now, those others may appear in lists of search results, but users are invited to pay for access to them. Librarians were angered at the change because the initial default was to include the $$$ results in the search and because JSTOR made no use of OpenURL standards, which would have allowed users to find the article in other databases that their libraries did subscribe to. The first of these issues has already been resolved by JSTOR in response to the uproar set off by this article.
I understand where people are coming from, resenting the crass intrusion of money into the disinterested provision of information, but really, information is not free. It only feels that way to the end-user because the library has covered the cost before it gets to you.