It appears then that the "finder" site may not be current. The Utah State website also lists more participating institutions than are shown at the originally linked site.

The "finder" site lists only 6 participants.

Utah State recognizes 10-1/2 institutions (MIT listed once, reappears for "Portuguese/Spanish")

Johns Hopkins, Tufts, and Carnegie Mellon don't admit they're not the only ones doing this on their front pages, but there may be more info somewhere within.
Sophia points back to MIT as a "precursor," but not to any others.

Interestingly, Carnegie allows you to register and receive credit using their open course postings (if you're already a student there).

So far as I've seen the others don't make quite the same offer, although the information posted should be the same one would receive "in class" if registered.

The listing of other participating institutions at Utah State appears to be due to their assuming the role of fostering the development of Open Course materials within the education community, rather than concentrating on the conversion and posting of material from their own curricula as others are doing. They have posted some of their own courses, but appear to devote most of their effort to spreading the effort - i.e. to recruiting other institutions to offer a consistent "product."

Obviously the listings mentioned thus far here don't even make a scratch on the surface of what's available. At About the MIT program:

"With 1,550 courses published as of November 1, 2006, we are still in a learning stage of this MIT initiative and we will benefit enormously from your feedback, as we strive to make MIT OCW as rich and useful as possible for our users."

If one wants details of the history of the courses, the best sources probably would be the two principal sponsor foundations. They seem to be cited by all the institutions involved.

John