Via Boing Boing, Cathy Guthrie, Woody's granddaughter, says she loves the JibJab parody of her grandfather's song.

I can speak for myself and my immediate family including my Dad, that we all love it! We've all seen it and passed it along to our friends and family. It's incredibly clever, funny and a nice break from the heavy tones of politics going on right now.... That parody was made for you and me.

Copyright being what it is, however, what Arlo and Cathy think doesn't matter. Nor even what Woody would think were he still alive. Once an author has transferred copyright, barring a termination of transfer, the author's wishes are irrelevant. Woody Guthrie, like many authors publishing commercially, had probably transferred what rights he had to his publisher for contractual royalites, but leaving his heirs no say in the uses allowed of his works.

The alienability of rights may be better than the European droit d'auteur, from which an author can't escape even if he or she wants to, but it probably wasn't foremost in the minds of the Congress that passed the Sonny Bono Copyright Term Extension Act 'for the children.' It's worth remembering, again, that artists and copyright holders aren't always the same people.