Yahoo! Pattern and UI Libraries

Yahoo! has really taken it to the next level in terms of reaching out to the developer community. As I mentioned earlier, there’s the new User Interface Blog and I coincidentally stumbled on the Graded Browser Support article around the same time.
Digging deeper I found the Design Pattern Library which Yahoo! defines as “an optimal solution to a common problem within a specific context”. The pattern library describes a problem and the best approach to undestanding and solving it.
Current examples include: auto-complete, breadcrumbs, drag and drop modules, module tabs, navigation tabs, object pagination, search pagination, object ratings, and writing a review.
The examples are sectioned into: when to use, the solution, the rationale, and accessibility. A sidebar includes links to related patterns, where Yahoo! has applied it to their own sites, a related blog article, and code examples.
Coupling the Pattern Libraries are the UI Libraries with in-depth examples and BSD-licensed code available for download.
These libraries are shaping up to be an essential resource for developers and designers alike!
Yahoo! Design Pattern Library
Yahoo! UI Library