The documentation indicates that the project's javaVersion is driven by sourceCompatibility, but I don't see that in practice ... it's always "1.5" (not even "1.6" as the documentation claims).

That's in 1.0-m-3.

http://www.gradle.org/releases/1.0-milestone-3/docs/dsl/org.gradle.plugins.ide.idea.GenerateIdeaProject.html

At the moment ideaProject.javaVersion is driven by project.sourceCompatibility if java plugin is applied. If java plugin is not applied then it defaults to 1.6. The current default for project.sourceCompatibility is 1.5. The documentation mentions that and I think it is correct

I think the improvement should achieve 2 goals:

1. Default the language level to the idea.project.javaVersion
2. Expose nicer way to change the language level. Currently (milestone-3) you have to do it like that:

idea.project.ipr.whenMerged { project ->
  project.jdk.languageLevel = 'JDK_1_5'
}

But it should be as simple as:

idea.project.javaLanguageLevel = '1.5'

I'll try to squeeze it to milestone-4