With a few lines of code you can grab your preferred libraries without having to download or host them yourself. You can even specify a specific version.
- jQuery UI
- Yahoo! User Interface Library (YUI)
- Ext Core
- Chrome Frame
I now regularly use this method to include jQuery and the jQuery UI and the speed is definitely comparable to hosting it yourself.
Here's an example of including jQuery 1.3.2:
It also parses as valid HTML.
No need to worry about downloading another copy of jQuery just include the lines above to get the version you need.
John Resig also mentioned in the first jQuery podcast that eventually core plug-ins and add-ons will also be available across the CDN so look forward to seeing that in the near future also.