Thanks to Sahoo, our OSGi applications expert and one of our most active participant on the mailing list, we now have an all-in-one Enterprise OSGi Applications in GlassFish guide document packed with useful content (a first edition of the OSGi & GlassFish definitive guide in a sense ;)
This document focuses on the OSGi Enterprise features of GlassFish, also known as hybrid applications. This includes WAB packaging, JPA bundles, EJB as OSGi bundle or service, type-safe and dynamic injection of OSGi Services using Java EE 6's CDI, exposing HTTP/JTA/JDBC/JMS as OSGi services, tooling and more.
You can find this document and more linked off of the main OSGi page on the GlassFish wiki.
To learn more about OSGi in the Enterprise, I highly recommend OSGi in Action: Creating Modular Applications in Java.
(Article copied almost verbatim from The Aquarium)