I was contacted by Packt Publishing back in November to review a book,
jQuery Reference Guide.
Unfortunately I've been too busy to do so. I finally admitted defeat, and emailed them back today, letting them know I would be unable to review the book, and offering to pay for the book that they generously provided.
I have skimmed the book, and it does seem to be a good reference. It doesn't however seem to mention what version of jQuery it is based on. That said, I do recommend the book if you already know javascript and DHTML, and want a quicker way of writing client-side code.