I got my copy of the 2005 edition of Hertzian Tales earlier this week (seems a bit early as it supposedly wasn't due till March - not that I'm complaining). Its pretty much the same as the 1999 edition. There is a new Preface. The layout is clearer, the text more readable and most of the images are larger. If you are (like me) a fan of Dunne and Raby you need this book.
Dunne, A., Hertzian tales: electronic products, aesthetic experience and critical design. 2005 (The MIT Press: Cambridge, Massachusetts).