bumppo writes "Matt Warner, a Mac developer and IT guy, writes about his experience trying to use the DMCA against a much larger software company that unilaterally lifted his TV tuner/converter app and bundled it with their hardware product, even hawking it on the side of the box. He explains why he didn't get very far, and sees plausible implications for the GPL."
One lesson here seems to be that though registration of copyrighted materials may not be necessary for them to be given legal protection, it goes a long way toward preventing such usurpation. (Note that the FSF is careful to copyright the code it releases under the GPL.) And DMCA or not, shareware and other non-retail software has been incorporated into collections without permission quite a bit before.