For $25, this guide walks you through the basics of jQuery

http://tekpub.com/preview/jquery?ref=lounge

Read it here

Some very cool jQuery plugins...definitely starting to challenge flash:

http://www.noupe.com/jquery/35-useful-jquery-plugins-for-slideshows-graphs-and-text-effects.html

Marc Grabanski has a great presentation on jQuery for those interested in dipping their toes in before getting started:

Link to Marcs Presentation