Their own self-promotion from http://java.sun.com/products/java-media/3D/: " Developers can easily incorporate high-quality, scalable, platform-independent 3D graphics into Java technology-based applications and applets. The Java 3D application programming interface (API) provides a set of object-oriented interfaces that support a simple, high-level programming model. This enables developers to build, render, and control the behavior of 3D objects and visual environments. By leveraging the inherent strengths of the Java language, Java 3D technology extends the concept of "Write Once, Run Anywhere" to 3D graphics applications."
White Papers / Guides / Presentations:
http://java.sun.com/products/java-media/3D/collateral/
VisAD and some other scientific visualisation tools use this.
Note: not used in FenFire LibVob? because too slow to make JNI calls when dealing with OpenGL there.
Not supported on macosx yet, because of licensing issues with Sun they've been reported to say. There's a beta version for Linux. People talk about this being supported in mobile phones.
Of course there is also Java2D