I wish to clarify something about the Sono Bono Copyright Extension, or any copyright law, for that matter.
The copyright amendment only affects works that have not ALREADY fallen into public domain. Once a work becomes public domain, it stays that way and cannot be 'resurrected'. There has been some misinformation posted on this subject.
Basically, any work that was published before 1923 had fallen into public domain by 1998, based on the old 75-year copyright term. The 1998 Sono Bono law cannot affect these works. (There are a few exceptions, but I don't want to delve into them here.)
I am a member of ASCAP and was NOT in favor of this copyright extension act. Copyright terms are getting longer and longer, primarily due to the arrogance of a few descendants of famous composers who can't bear to see their royalties end and organizations like ASCAP and BMI who protect the interest of the big publishers such as Warner Bros. I wish they'd get a life.