The project was always intended to help ensure continuity of Java on Mac OS X; integration with OpenJDK being the means to ensure ongoing support and encourage Sun/Oracle's adoption of official support for the platform.
I've updated the project goals on the home page accordingly:
- Support for Java 6 Development on Mac OS X 10.5 and later (including Mac OS X 10.7 Lion)
What do you mean exactly by "purpose-specific"?