The YUI team has posted YUI 3.1.0PR1, a preview of the upcoming YUI 3.1.0 release. The purpose of the preview release is to provide a stable snapshot of YUI 3.1.0 for developers to take for a test drive and provide feedback ahead of the official production release. The preview release consists of a .zip file available on the YUI 3 download page that contains the source, the built files, API docs, updated ReadMe files, and a few examples for each component. The build can also be accessed via the CDN by referencing http://yui.yahooapis.com/3.1.0pr1/build/... . At this time we do not expect to be making any additional interface changes in YUI 3.1.0. Some preliminary testing has been completed but we expect to add a few additional fixes between now and the official release based community feedback and additional integration testing being done in-house.

One important note for developers who are already working with YUI 3: In bringing the widget infrastructure to production quality for 3.1.0, we changed the default prefix used for CSS classnames in YUI 3 from yui- to yui3- to avoid CSS classname conflicts in situations where YUI 2 widgets and YUI 3 widgets are deployed on the same page. The YUI 3.1.0 preview release contains this change.

Note also that the documentation on the YUI 3 developer site still reflects the YUI 3.0.0 production release. This content will not change until the official 3.1.0 launch. However, you will find details on the changes included in YUI 3.1.0 by referencing the updated API docs available in the .zip download. There is also a ReadMe digest available summarizing all of the change notes developers have added to their component ReadMes for YUI 3.1.0. Each component also includes several examples to demonstrate some specific use cases of the code.

Some highlights of the YUI 3.1.0 release include:

• The Widget infrastructure is now production quality.
• Widget-parent and Widget-child are two widget extensions that have been provided in beta form with this release that allow for hierarchical widget implementations.
• The TabView widget has been introduced in this release and can be used as a reference implementation for implementation of progressive enhancement and accessibility for widgets.
• Slider has been enhanced to include several alternative visual treatments.
• The Intl Utility makes its debut supporting string-based language packs that can be used for internationalization of custom modules.
• Synthetic event creation and delegate enhancements have been added to Event.
• IO now supports synchronous transactions for same-domain requests.
• Loader has been updated to provide multiple combo domain support (where you have multiple servers, each supporting combo-handling for their content), support for dynamically loading language packs, per-component metadata, and better support for YUI 3 Gallery modules.
• A new Sortable List Utility.
• Ports of SWF and SWF Utility from YUI 2 to YUI 3.
• Updates to Test which include test duration tracking, support for JUnit XML test results format, TAP test results format and several new methods added to TestRunner.

Should you encounter any defects or come up with additional enhancement requests as you work with the YUI 3.1.0 preview release, you can file a ticket in the YUI 3 ticket database. Please be sure to set the observed version of the library to 3.1.0 PR1 as you enter the details for the ticket.

We hope you enjoy exploring YUI 3.1.0PR1. We look forward to hearing your feedback.

yui3-1914 -- I'll add another one that specifically calls out 3.1.0pr1.

According to the calendar, sometime next week:
http://yuilibrary.com/projects/yui3/calendar#calendar