It took a bit longer than anticipated, but we have updated the repositories behind GlassFish v3 Preview (STABLE from glassfish.sun.com). You are most likely to notice this through the see new SoftwareUpdate tool, but you might also see it through the GUI UpdateTool or the embedded UpdateTool, or do it manually via the CLI. Full details in Alexis writeup and Abhijit's announcement. The whole thing has been working very well for me in recent builds but this is software, so please let us know if you experience any issues.

Alexis and Paul have updated the GlassFish Release Feature Table that compares GlassFish v2, v3 Prelude and v3 Preview. My shortened summary is still applicable: v2.1 is for production deployments, v3 Preview is a beta for v3 final and v3 Prelude is/was a transitional release...

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 :-)