I’m particularly interested in the first item, which sounds intriguing.
Pre 1.4, jQuery supported adding attributes to an element collection via the useful “
attr” method, which can be passed both an attribute name and value, or an object specifying several attributes. jQuery 1.4 adds support for passing an attributes object as the second argument to the jQuery function itself, upon element creation.
A few other things that have been added are: more live() events, animation queue delays, a method to check whether an element contains another element with a certain selector, and a way to remove elements without destroying the data.
It certainly is a feature-packed release.