By now it is not news (at least 5 blog entries have already announced it)
I just wanted to point out a couple of new things to look for in this release:
If you scroll down the JDeveloper 11 home page on OTN you'll see pointers to two new developer guides we are working on - you can get the current draft there and it might help you in your 11 learning experience.
There is an improved subversion support in this release (incoming window, branch, merge) - so check it out and let us know if you find any bugs.
There are new data visualization components - the gauge component is currently my favorite one to demo.
There is an updated version of the ADF Faces Rich Client Components demo - better organized and including the tag docs.
There is now support for migration from 10.1.3 - so back-up your projects and give the migration a run. Let us know if you find any issues.