Some of the items featured include Galileo's conviction, the letter instrumental to the Anglican schism begun by the affairs of Henry VIII, the document proclaiming the dogma of the Immaculate Conception, and the bull of Martin Luther's excommunication, among many other very cool things. If you can't make it to Rome, or simply want to whet your appetite for the real experience to come, the exhibition's well-produced website features a selection of the items, which you can browse here. You can also buy the exhibition catalog here.
I should have mentioned in the last post that the Vatican's reputation for clunkiness in web design also extends to the Vatican Museums (whose site seems to be stuck in the '90s), and to a lesser degree, the Vatican Library (which recently underwent a massive renovation a few years ago). The Vatican Secret Archives, on the other hand, has got itself a little more with the times with its very sleek website.
I dearly hope that I am lucky enough to have the opportunity to visit this exhibition sometime in the coming months.