Hot on the heels of my post about the AJAX toolkit spectrum comes news that Yahoo! has released their own AJAX toolkit as well as a very cool web page design pattern catalog.
Some non-surprises:
All these different implementations of the same core set of capabilities at best means learning lots of ways of doing the same thing and at worst means incompatibility between components from different libraries.
BTW, last week I wrote that using a text-based high-level scripting language like Javascript in the browser "encourages business models where the in-browser code has little if any value." This release from Yahoo! supports that point. While their mapping component is subject a strict Terms of Use, their UI components were released with a liberal open source licence. I doubt that's a coincidence.