The TCK is a key piece of the puzzle in strongly safeguarding compatibility for anything Java. Generally speaking, companies that make money from compatible Java technology implementations have to pay license fees to run the TCK. This license fee is one of the few sources of money that helps pay the bills for the JCP/TCK process itself.
Nonetheless, Sun and now Oracle has always had a way to grant TCK scholarships for (primarily open source) non-profits and academic institutions. For example, Apache and OW2 have long had Java EE TCK scholarships to certify Geronimo and JOnAS. Oracle recently extended the gesture of good will to the open source community by granting TCK scholarships to the Eclipse Foundation for certifying EclipseLink and Virgo.
Most of you are probably already familiar with EclipseLink - it's the open source JPA reference implemention seeded via a code contribution from Oracle TopLink. You probably are not that familiar with Virgo in comparison - it's an open source Java application server from the Eclipse Foundation. Most of you will probably remember that Virgo was created when SpringSource decided to donate dm Server to the Eclipse Foundation a few years ago. Thanks to the TCK scholarship, Virgo will now aim to become another great Java EE Web Profile application server choice for you instead of just a focus on OSGi and Spring.
This is what Mike Milinkovich, executive director of the Eclipse Foundation, had to say about the grant: "It is important for the Eclipse Foundation to provide our community with the tools they need to enhance developer productivity. As a key contributor to EclipseLink and other projects, Oracle has been a strong supporter of our efforts. Through the Oracle Compatibility Testing Scholarship Program the Eclipse Foundation now has access to the resources we need to achieve Java EE Web Profile compatibility both for Java EE 6, as well as the forthcoming Java EE 7".
You can read about the details in this official press release.