You can see my response in the comments on this post in the ExtJs blog. In between mojoPortal official releases I had upgraded to ExtJs 2.1 in svn but as soon as I found out they had pulled a bait and switch I reverted to the 2.0.2 release which is still under the LGPL. According to their post they would lead you to believe that its ok for mojoPortal with the open source exceptions clause but it doesn't satisfy me because I want others to be able to package their closed source features with the open source mojoportal. This is allowed by the CPL but anything GPL would not work.
So I have no plans to ever upgrade ExtJs unless they change their mind on the license. I've used Dojo before I got into ExtJs and it didn't seem as well done.
I'm more inclined to get behind OpenExt.
I wish they would come to their senses at ExtJs.