Aside from the he said/he said aspect of this tiff, I'd like to hear from you published scholars out there: What is standard procedure when an editor is compiling a book of academic essays like this? I'm sure that, at the least, Pennock's publisher contacted Dembski's publisher, if only to find out where to send the royalty check? (Or do authors who got their essays included in a book normally get royalty checks?)
Who else should we ping who would know about this sort of thing?
Usually, essays or chapters included in research books or text books are written upon invitation from the editor. Royalties are extrememly rare. It's considered an honor if not a time-intensive obligation to write such a chapter.
In this case, the compilation doesn't seem to be of that type, but rather a work by a single author who used previously published essays to put forth his thesis. If the copyright is held by another publisher, Pennock is under no obligation other than normal social protocol to contact Dembski.