I've starting getting responses on my copyright inquires from various archives around the country. I am also looking at digital collections. So far, I have found three good examples: 1) the Mark Twain papers at Berkeley, who have copyrighted everything through microfilm before the unpublished public domain deadline (except the incoming letters, which they did not publish, which is potentially very cool for scholars); 2) the Library of Congress, which has done an amazing job of giving specific copyright info for each of its collections; and 3) the NYPL, which has no copyright info on the materials I looked at (the theatrical papers collections), and when I emailed them, replied that these things were complex, and suggested internet sites to help me figure them out.
The first is proactive; the second is friendly and also since many are digitized collections, the LofC had to figure out the rights themselves (and so why not share the info, I guess); the third is traditional -- housing papers, restricting and allowing access, but not getting involved in the copyright issues and leaving it to the scholars.
One can see how the internet is benefiting scholars in this scenario (Library of Congress example). It is creating an interesting tier system of access, copyright, and the unpublished public domain. The third example is almost worse than the MT papers, because at least there one has a clear sense of the parameters. How many scholars are going to know or take the time to figure out the copyright for 1960 radio plays?
For more specific info and the links to these sites, see my posts at http://academiccopyright.typepad.com. (I am still having trouble over here)