The first sentence really stops me from reading it

jQuery is a very powerful library, but some of its powerful features are obscure, and unless you've ready the jQuery source code, or my new book jQuery Pocket Reference, you may not know about them.

Why don't you give me the article first, let me read it, get amazed by the techniques and then find out about you and your book and feel like I need to read another book.

This way I feel like you are trying to sell me your stuff.