Really? ANOTHER jQuery intro? How about just RTFM, since it covers way more than this ever would. Anyone serious about jQuery is going to end up using it anyway, so let's cut to the chase.
By this logic, you will never need technical books, only manuals.
I think a introduction could be great for someone who is beginner and want to start from the ground up. If you send them to api.jquery.com, they will get completely lost. You are understimating the amount of knowledge required to get started with jQuery (you have to know HTML, CSS selectors, JavaScript and then the actual jQuery)
I, for one, am happy this link appeared here. I am one of those: know a bit of CSS, a bit of HTML, a bit of JavaScript and I want to know what this jQuery stuff is all about. Going to the API? Nope, I'd assume this takes at least an afternoon; which I don't have.
Have you read the docs, ever? They have any implementation you'd need. Want to write a plugin? There's a document for it. Plus the comments are actually useful.
http://api.jquery.com