The Complete Guide to Google Wave is book authored by Gina Trapani (Lifehacker fame) and Adam Pash. This book is freely available for reading online. The book is divided into 8 comprehensive chapters and 2 appendices. A very good book on Google Wave indeed.
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Bookmark the link for future reference and read the free online book to get to know Google Wave inside-out. "The Complete Guide to Google Wave" book will be available in PDF and print sometime next year.
Now if only someone will send me a Google Wave invite.....