Awesome. My problem is I've been waiting for 4.0 soooo long I ended up making my own jQuery with some key differences:

  * Animations, tweens, timelines use pure CSS, instead of jQuery's custom system.
  * Use one element or lists transparently.
  * Inline <script> Locality of Behavior. No more inventing unique "one time" names.
  * Vanilla first. Zero dependencies. 1 file. Under 340 lines.

https://github.com/gnat/surreal

That said, it's fantastic to see 4.0 here, and I'll certainly be upgrading my many sites that use it!