WP 3.1 and Enqueueing jQuery

Theme developers, take note: Mark Jaquith gives some useful information regarding coreCore Core is the set of software required to run WordPress. The Core Development Team builds WordPress. jQuery updates in WordPress 3.1:

WordPress 3.1 uses jQuery 1.4.4, and jQuery UIUI UI is an acronym for User Interface - the layout of the page the user interacts with. Think ‘how are they doing that’ and less about what they are doing. 1.8.6. You should check your plugins to see if anything broke.If you were enqueueing jquery-ui-core and using the “widgetWidget A WordPress Widget is a small block that performs a specific function. You can add these widgets in sidebars also known as widget-ready areas on your web page. WordPress widgets were originally created to provide a simple and easy-to-use way of giving design and structure control of the WordPress theme to the user. factory,” or something that depends on the widget factory you will have to update your pluginPlugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party to enqueue jquery-ui-widget instead. In jQuery UI 1.8.x, the widget factory was separated from jQuery UI core. Please examine wp-includes/script-loader.php to see the entire dependency tree.

If  these changes affect your Theme, please update accordingly.