Wikipedia has an interesting paragraph on the circumstances whereby his autobiography will not enter into the Public Domain as scheduled, but later, due to some "gaming the system".
I remember when it first came out, which was surprisingly recently, in 2010.
They published it in secret in 2001 so that it is not considered "unpublished" and doesn't enter public domain in 2003. Although I don't understand how "publishing in secret" is still considering publishing.
searching for gaming, public domain, and copyright all come up empty - do you have more details.