Updated December 8.
jQuery UI 1.8.16
jQuery UI has been updated to the latest version, and all UI components are now included in core, including widgets and effects. This will make it a lot easier and simpler for plugins using UI components that are not used in core as they will be able to just enqueue whatever they need. (For reference, WordPress 3.2 included part of 1.8.12.)
The wp_editor() API
Since the last post there have been some bug fixes for wp_editor(). This is an updated API for both TinyMCE and Quicktags that outputs all parts of both editors in the same way as used on the Add / Edit Post screens. Plugins will be able to use the WordPress editor anywhere — including rendering the Visual/HTML tabs and the links to upload files and show the media library.
$content = 'The content.';
$editor_id = 'foo';
$args = array(); // Optional arguments.
wp_editor( $content, $editor_id, $args );
Yeah, that’s it (though of course, you need to save it as well). Of note, there’s one pretty big gotcha: If you use wp_editor() to render the visual editor in a meta box, you risk problems. TinyMCE does not support being detached/moved in the DOM, which would occur when a meta box is dragged. (I’d look into the edit_form_advanced hook to render additional editors.)
For more, there’s a nascent Codex page on the API.
Quicktags was refactored to make it fully multi-instance compatible (#16695). I think it still needs a Codex page, and I’ll ask @azaozz to post a tutorial here on how to use the new methods, and what before/after looks like in terms of converstion.
When switching it to json_encode(), we opened up the possibility for encoding errors, so some changes were made to make this more backwards compatible.
If you have previously used wp_localize_script() to pass arbitrary data (rather than localized strings), consider switching to wp_add_script_before().
Edit, December 8: wp_add_script_before() was removed.
The old SWFUpload has been replaced with Plupload. Nothing here has really changed since the previous post, other than strings and the presentation of the drop zone.
wp_enqueue_script() now works mid-page
Yes: wp_enqueue_script(), called mid-page, will now enqueue the script into the footer. This isn’t new from the previous update.