This is a full-featured development environment for Ceylon, with I guess everything you use regularly in your Java IDE, including interactive error reporting, incremental build, syntax highlighting, proposals, quick fixes, refactoring, searching, wizards, hover help, debugging, and much more. It even has a major feature that your Java IDE doesn't have: deep integration with Ceylon's module and module repository architecture. (No more futzing with the project build path!)
I'll have more to say about how we were able to engineer an entire professional IDE for a new language in less than 6 months with two part-time developers in a future post.
Once again: thanks to David Festal for all his hard work, and to SERLI for their support.