Well, Monday the ExtJS team released 2.2. Much more than a minor dot release, 2.2 addresses several bug fixes, nice increases in perfomance, better support for Firefox 3, and several new components and examples.
Some of the new components include CheckBoxGroups and RadioGroups for forms, a new History object for managing the back button (a common issue in RIAs), a new FileUploadField, and even an XMLTreeLoader to automatically create Tree components from an XML Document. There are several new examples, to show developers how to use these new components, better information on how to implement Drag and Drop, and more.
ExtJS 2.2 is fully backwards compatible with the 2.1 release. I tested several applications last night, seeing definite speed increases. Really well done. (There also appears to be some speed improvements when implementing ExtJS within Adobe AIR applications as well, from my testing.)
I'll have a lot more info on ExtJS coming in the near future, so watch this space;)