As Curtis put it: it is nice to be out of the 3.3 lockdown. It means that we can start writing some cool code and adding in some cool new features. Curtis already told you all about the cool new dragging and dropping. I will tell you about non-resource based context launching.
You might remember back in 3.3M6 when we added in the new feature for context sensitive launching, heck you might even be using the new feature. For all the good that it brought to the world, it did have a severe drawback; it did not work with project artifacts that were not resource based (had or could get a handle on an IResource).
What we want to do now (in the start of 3.4) is extend context launching to allow contributors the ability to tell us how to launch something. That way if we don't know how to launch foo.xxp you can provide a context launching participant to tell us how you would like it launched.
We are hoping that this will bring together the best of all worlds of launching and make it even easier for novice to expert users to make use of launching/development in Eclipse.