What's the Right GlassFish Release For You?
By pelegri on Jun 29, 2009
Alexis has a nice summary of the different GlassFish releases, explaining how to Choose the Right Release: GlassFish v2.1, GlassFish v3 Prelude or GlassFish v3 Preview. In a nutshell, v2.1 is for production deployments, v3 Preview is a beta for v3 final and v3 Prelude is/was a transitional release...
... but you want the full story, so check Alexis' Answers...
... or just ask Ask the Magic 8 Ball :-)