First off, I would like to point you to Tony Ng's blog. Tony Ng talks about the differences between Java EE SDK, Sun AS 9 PE, GlassFish and RI here and it is important to understand the differences : Tony's Blog
Now off to my blog topic. One beautiful administrative feature that I like in the GlassFish Beta release is the ability to deploy your own JMX spec compliant management objects (popularly known as MBeans). With this facility, you can pretty much add any new configuration and management behavior and deploy it to the application server. This is particularly useful when you want to add manageability to your own application environment. This provides tremendous power to the application environment, for example, to ease the pain of updating business services, such as, update newly available products in catalog, financial providers, etc. Access to these MBeans could be made using JConsole (directly access the MBean and invoke operations). Watch out for more in this area.
The administrative Command Line Interface utility and the browser based admin GUI provide respective ways to deploy the custom MBean.
In the command line interface (utility called "asadmin" located in the installation's bin directory) the relevant commands are :
asadmin "--help command-name"
command to read specifics on how to deploy your custom MBeans. The command line is useful when using scripts to automate such tasks.
In the GUI, login to the default url, typically http://localhost:4848, enter admin user and password, and then look for the link to "Custom MBeans" in the left hand side. This allows you to use the GUI's browser-based easy deployment wizard to deploy your mbean implementation.