For a book about "MOAR CODEZ!" you're giving Rob Sobers short shrift.

Rob seems to have done a great job translating the python-ness to ruby-ness, but Zed did the hard work -- he created the approach and wording for Python.

I haven't tried to compare them, but my interpretation of Zed's comments is that most of the text is still Zed's.

Edit: You might be short shrifting Eco's translator. Reading his stuff is hard enough, translating must be a royal PITA. </tongue-in-cheek>

Eco's work is tough. So, yes, maybe I'm undervaluing the credit of "translator".