The jQuery team has released a new version of their awesome framework – jQuery 1.5. While not seemingly as significant as the 1.4 release, they made quite a few major changes under the hood.
On top the various bug fixes and performance enhancements one of the major changes in jQuery 1.5 is a complete rewrite of the Ajax module.
Perhaps the largest change is that a call to jQuery.ajax (or jQuery.get, jQuery.post, etc.) now returns a jXHR object that provides consistency to the XMLHttpRequest object across platforms (and allows you to perform previously-impossible tasks like aborting JSONP requests).