I understand that Oracle GlassFish Server 3.0.1 product is the open source Glassfish + branding + some closed source components.
Is there any technical reason to purchase the commercial version? A JRockit license? Surveillance tools? Integration with other products?
EDIT: Personal experiences with the commercial product is highly valued.
As it was the case previously with Sun, Oracle offers GlassFish Enterprise Manager, a set of additional features for production, to its customers (now those acquiring Oracle GlassFish Server). You can get an evaluation copy of these additional feature at http://oracle.com/goto/glassfish
Other reasons to use the commercial offering include support for the JVM (Hotspot and JRockit) and patch releases for GlassFish (follow these on blogs.sun.com/glassfishforbusiness)
The main difference of course is the full support for commercial deployments. Using a product in a commercial environment without support is often not a good idea. The truth is though that open source GlassFish does have quite the community for support as well so the decision is really just up to you. How comfortable do you feel maintaining a server without being able to call someone if things go horribly wrong?
I have used glassfish several times in a production environment and I always was very happy with it. Guess it depends on which level support is required for your particular project.