This book presents all the arguments you might need to convince anyone, however sceptical, that following standards is the way to go when building websites. Jeffrey Zeldman obviously knows his stuff and is one of the foremost authorities in the field.
This book also stands out from the bulk of technical books by being funny and personal, without ever compromising the integrity of the text.
Sadly, his examples of browser (mis)behaviour are hopelessly out of date. That was true even when this revised edition came out in 2006, and makes all the once usefull browser speciffic workarounds pretty useless.
An updated version is expected later this year, so you would probably be better off waiting for that.