- A Task-Focused user interface, like Eclipse's Mylyn and even better
- Improvement in supporting Spring, Hibernate, Seam, Facelet, Flex
- Improvement in integration between Hibernate and Spring
- Improvement in Ruby and JetGroovy plugin
Even I want to see UML support in IDEA (support for popular diagrams, generate source code from UML, reverse engineering from source code, synchronize between diagrams and source code,...) but I don't think it will appear in Diana.
OK, now wait and see, in a few weeks later, they will post the road map for Diana.
Update: Added Facetlet, Flex