Feb, 02, 2011
To summarize, most of the improvements are in performance. A few new features have been added however. The one that caught my attention was the deferred objects API. This API allows for "you to work with return values that may not be immediately present (such as the return result from an asynchronous Ajax request)". Off the top of my head I don't really see a purpose to this, but I'm sure it has its place. The rewrite to Ajax also allows for multiple event handlers to be added to requests, which could lead to cleaner, better looking code.
A round of applause and a big thumbs up to jQuery for continuing to support such an awesome project.