OSGi functionality in JBoss AS 7 is provided through the OSGi subsystem.
The documentation of this functionality can be found at the JBoss OSGi documentation pages.
Integration with AS 7 and reference the the OSGi subsystem in the AS 7 XML configuration file can be found in the Application Server Integration section.
More information on the OSGi component in JBoss AS 7 can be found on the JBoss OSGi project pages.