The cat is out of the bag, and it is a cool cat - JDeveloper 11g is now out in production and you can get it from OTN: http://www.oracle.com/technology/products/jdev/index.html
But once you got it what's the next step? Where do you start?
One thing you can do is review some of the online demos we created to show off some of the new features: http://www.oracle.com/technology/products/jdev/viewlets/viewlet.html
If you want to get your feet wet and try it out then you can start with the online cue-cards inside JDeveloper (linked from the Help->Start Page) and you can also try some of our step-by-step tutorials that are out on OTN: http://www.oracle.com/technology/obe/obe11jdev/11/index.html
Now that you tried some of the features you might want to understand what is going on behind the scene and how this wonderful ADF things works.
For this we have the ultimate developer guide, previously known as the ADF Developer Guide, and now called the Fusion Developer Guide - available from here:
You'll also see there another developer guide dedicated to ADF Faces Rich Client.
Then if you have questions come to our online forum and ask - we promise to try and answer:
There are more demos and tutorials that will show up in the near future - so keep checking these pages over the next couple of weeks.