Here are the highlights:
- The new Layout Manager allows you to create multi-pane user interfaces that are collapsible and resizable.
- The Flash-enhanced File Uploader control might be known to you from Flickr and and allows you to easily batch-upload files and images with progress bars.
- The YUI Data Table performs faster and got new features, including horizontal and vertical scrolling, a paginator class, drag and drop columns and an API to access, add and remove columns.
- The Image Cropper control allows you to pick a part of an image to be cropped server-side
- The Cookie Controller provides a wrapper for all things to do with cookies
- The Slider Control got updated to support multiple handles to define a range rather than just a state.
In addition to that, some of the components left beta status. These are the Get Utility to retrieve scripts and style sheets on the fly, the ColorPicker Control, the JSON Utility to validate JSON, the ImageLoader Utility to load images on-demand to increase page performance and the YUI Test Utility.
The really detailed report on all the changes is available on the YUI list/forum.
If you want to have a quick glimpse of what the Layout Control allows you to create, check out the demo application interface simulating simulating Yahoo Mail.