Collaborative partnerships and authoring...

As I began to think about collaborative art-making after last week's class, one of the first things that came to mind was a kind of two-person/artist collaboration that I have heard about several times in the past few months. This type of collaboration involves one artist beginning work on a piece and then sending it to the other artist to finish. I don't know how long this exact form of collaboration has been prevalent, but it certainly seems to have some popularity at the moment.
I visited a gallery this summer with a class I took, and one of the main exhibits was one such collaboration. It was called "Cross Country" and involved two artists working on opposite sides of the country. They would ship fairly large pieces back and forth in order to complete the artwork. While the show was interesting, a number of my classmates expressed their desire to know more about the process. They wanted to see some more evidence of the collaboration than just the final pieces (such as a picture after the first stage). I agreed that it was hard to understand where the artist's individual mark was made on the art (these pieces happened to be sculptures), but in the context of this class, I am beginning to wonder if revealing any more than just the sculptures themselves would go against the whole purpose and point of the collaboration and the "de-authoring" that can occur.
Certainly most exhibits do not include an illustration of the artistic process, so why then, should we expect to see an explanation of a collaborative artistic process? The more I think about this question, the more I see an argument for both sides. I am curious as to what others think? Should collaborative artwork always involve an element of de-authorization? Does it always involve this element? In the case of the exhibit I viewed this summer, I would argue that there was a significant authored presence, just split between two artists. In this case, I do think it was somewhat natural for viewers to wonder about the nature of the collaboration and the process the artists went through. Obviously this can be true for one type of collaborative work, and not so for others (such as the Happenings that Kaprow wrote about in this week's reading). Is anyone drawn to a certain form of collaboration?