If you haven’t done so already, head over to the YUI Blog for the official announcement. I am proud to have made a (very modest) recent contribution to the library by porting the browser history utility to YUI3 (take a look at the source code) By the way, this new version of the browser history utility supports Opera and IE8 (in both quirks mode and IE7 standards mode) Moreover, it has more features than the YUI2 version, should be easier to use, and weighs a few hundred bytes less (after minification with the YUI Compressor) I’ll try to find some time in the next few weeks/months to write a bit more about YUI3 in general, and the new browser history utility and the YUI Compressor. Stay tuned!