Production quality at last, from one of the most promising JavaScript toolkits we've ever used.

From Yahoo:  "We’re pleased to announce today the general-availability release of YUI 3.0.0. YUI 3’s core infrastructure (YUI, Node and Event) and its utility suite (including Animation, IO, Drag & Drop and more) are all considered production-ready with today’s release."

Source: http://www.yuiblog.com/blog/2009/09/29/yui-3-0-0/