The long awaited and the most looked upon version of GlassFish released today. GlassFish v3 fully implements Java EE 6 specification which means EJB 3.1, Servlet 3, JAX-RS, JPA 2, Contexts and Dependency Injection for Java EE, Bean validation, Java EE profiles and so on.
GlassFish is not only the most up to date application server but it also benefits from a very good architecture. GlassFish architecture provides extensions points and contracts which 3rd party developers can use to add functionality to GlassFish (even the administration console is plubable).
In addition to Java EE profiles, GlassFish v3 is also available as an embedded application server which we can use for testing purpose or any other kind of in process use cases.
What I like the most about GlassFish is its close integration with many other well developed products like OpenESB, OpenSSO, IDEs, and so on in addition to its superb performance and administration channels.
GlassFish v3 adds another reason to make one consider it as the prime option for deploying simple and complex application, and that is its extensibility which so far made it possible to host different kind of scripting language based applications like application based on RoR or PHP in the same process which hosts the Java EE applications.
Like GlassFish v2, Sun Microsystems provides support for GlassFish if you need a higher level of assurance and guranteed support. to get more information on the provided support model take a look at GlassFish Enterprise Home-page.
And if you are interested there is a GlassFish V3 Refcard published by DZone and authored by me which introduces GlassFish v3 in more details and gives you all you need to start working with GlassFish v3.
I have an Upcoming Book about GlassFish which is due to be published on April 2010 by Packt Publishing. The book mainly discuss GlassFish security (administration and configuration), Java EE security and using OpenSSO to secure Java EE applications in general and Java EE web services in particular.
To learn more about Java EE 6, you can take a look at Sun Java EE 6 white paper located at: https://www.sun.com/offers/docs/java_EE6_overview_paper.pdf
Another way for you to meet GlassFish folks, other GlassFish community members and to learn more about GlassFish v3 is to join the Virtual Conference about GlassFish v3 which is supposed to take place on 15th of December.