Lots of opinions.  Here's mine.

After the dust settled, I believe protection was extended to compositions
that had been properly renewed prior to 1978.  The extended period was 75
years after the initial copyright.  So in January, that will make things
copyrighted prior to 1921 public domain.

There is a "copyright office home page" on the net that contains a bunch of
circulars.  One of them (I believe) deals with public domain issues.

Cheers,

George Bogatko - gbogatko@intac.com
                 http://www.intac.com/~gbogatko