I have catches this YUI theater video a few days ago, promoting a new JavaScript book. The podcast is great, and the High Performance JavaScript book is a must have for any serious JavaScript developer
Although I knew about 70% of the tricks the authors describe here, I still gladly spend the $35 at Barnes & Noble to own this book as a reference. It is a nice overview, of what really matters, in optimizing your JavaScript app. I like the fact that it is written from several perspectives, and each author really gives his best.
Here are the chapters