jQuery UI 1.5b4 gets released with integrated jQuery Enchant (which was the missing part of ui: a library completely devoted to rich effects.)! Great to see this, as the role of jQuery UI now can be compared to what script.aculo.us is to prototype, but then to jQuery of course.
Above that the jQuery UI site has been revamped, and now features a download builder, just as ExtJS has 🙂
(BTW: jQuery 1.2.4 to be released on May 15th ;))