Julian Aubourg 3.99
If you're into asynchronous programming, you'll love jQuery 1.7! Not only do Deferreds gets progress callbacks, but you also get a brand new constructor, $.Callbacks, that covers pretty much any need you may have when it comes to listing and firing callbacks in your application. Sounds too good to be true? Yet another thingy that's impossible to grasp? Fear not: Julian will walk you through it and make you the first persons in the world to know about $.Callbacks in and out!