After a long wait, the awesome jQuery library has finally been committed to Drupal core. jQuery 1.0 will be part of the next major Drupal release, for which the code freeze is about to begin.
What is jQuery I hear you ask:
This is a very exciting development for Drupal opening up a whole world of new user interface improvements. As an example of some of the things that can be done have a look at Steve’s colour picker widget. Now that’s some cool stuff.
There’s more info on jQuery and how it will fit into Drupal in the Lullabot podcast with jQuery’s author John Resig.