[p9idf]

Why do you find that so repugnant that it moves you to write resentful comments about it? The entire point of researching and publishing computer operating systems is to discover and share new methods and ideas. I doubt that the Plan 9 authors published dozens of papers and gave countless lectures in order to discourage others in their field from building on their work. They didn't discuss their ftp filesystem multiple times in their publications in the hopes that nobody would ever implement anything like it ever again. That the Hurd authors profitably exchanged ideas with another operating systems group is beneficial to everyone and shouldn't fill you with spite.

[geofft]

Credit / acknowledgement of related work would be nice, and not just because it's the right thing to do. It's good for readers who aren't aware of the related work. It's good for readers who are aware of it (so they can understand the differences, or so they merely know that this author is aware of that author's work). It's also very good for the project's own future maintainers to be aware of similar efforts, especially those that tend to publish what works and what doesn't.

[pjmlp]

You mean like the many breakthroughs being made in Linux that are actually mainframe ideas?