Joshua Bloch spoke out our local Java Users Group recently (after leaving Sun for Google) and indicated that he did plan to eventually release some sort of update. I'm not sure if this would be a second edition, or a second volume. (I.e. will it be a replacement with some new stuff, or all new material?) Either way I don't think it's happening soon. The original Effective Java came from years of seeing common errors encountered in Java. Perhaps we won't see a new edition until we've seen several years of mistakes with generics.
I don't know who controls the rights to release a new edition or volume in this case. It all depends on the nature of the contract Josh signed. But even if Sun has control here, I doubt it's in their interest to prevent Josh from updating Effective Java if he wants to. [ October 04, 2004: Message edited by: Jim Yingst ]
Yes, buy this book, read it and then read it again. It is basically a set of rules which will improve the way you program. The rules are cross referenced and the book doesn't have to be read sequentially. I found that on the first go through the book I was jumping back and forth quite a bit. That is why re-reading this book is a must, to ensure that all the information sinks in.