Features of Glassfish Application server:

1. Fastest open source application server (883.66, highly scalable).
2. Centralized management of clusters and instances distributed across multiple servers.
3. Microsoft .NET 3.0 interoperability
4. Java Business Integration and Open ESB
5. Call flow analysis for diagnosing performance problems
6. High performing message queue implementation (Open Message Queue), with a highly available message store.
7. SIP Servlet support and Telco Support via SailFin
8. Very small footprint and flexibility via modularity in GlassFish v3.

here is the video which delineate Glassfish Application Server more in detail