Yahoo! announced some cool stuff last week. In his blog post Yahoo! UI JavaScript treats Simon Willison writes

The Yahoo! Developer Network was updated yesterday with a veritable gold-mine of Exciting New Stuff, coinciding with the launch of the brand new Yahoo! User Interface Blog. #

Here are some of the highlights: #

• Mature, extensively tested cross-browser JavaScript libraries for animation, event handling, DOM wrangling, XMLHttpRequestDrag and Drop. # and

• CSS-skinnable UI controls built on those libraries: Calendar, Slider and TreeView. #

• A library of documented design patterns for modern web applications. #

• A description of Yahoo!'s Graded Browser Support policy, which should be of great interest to anyone who cares about Web Standards, semantic HTML, accessibility, progressive enhancement and unobtrusive JavaScript. #

The code is all under a BSD Open Source license, which means you can use it freely in your own projects, including for commercial development. #

This is a fantastic contribution to the Web developer community by Yahoo!. It's taken me a week to blog about it because I wanted to try it out first. Unfortunately  I still haven't gotten around to trying out the code but I decided to give it a shout out anyway. This is basically what I expected Microsoft to provide developers with Atlas but not only has Yahoo! done it first, it has done so in a way that is completely free (as in speech and as in beer). Wow. 

The folks at Yahoo! are definitely understand what it means to build a developer platform and a developer community on the Web. Kudos to everyone involved in getting this out.