From the Journey of 1000 Miles... dept.:
...This week the IcedTea Project reached an important milestone - The latest OpenJDK binary included in Fedora 9 (x86 and x86_64) passes the rigorous Java Test Compatibility Kit (TCK). This means that it provides all the required Java APIs and behaves like any other Java SE 6 implementation - in keeping with the portability goal of the Java platform. As of writing, Fedora 9 is the only operating system to include a free and open Java SE 6 implementation that has passed the Java TCK. All of the code that makes this possible has been made available to the IcedTea project so everyone can benefit from the work.

The Java TCK is a complex suite of tools and documentation that verifies that Java implementations conform to the Java specification. It consists of more than 80,000 tests and over 1 million lines of code.

jboss.org

iced-tea.org