The OSGi framework specification forms the basis of the Eclipse Runtime. As of Eclipse 3.0, the Runtime is fully based on the OSGi notion of bundle (equivalent to Eclipse plug-ins). The OSGi framework implementation in Eclipse 3.0 is fully compliant with the OSGi framework specification R3.0. The OSGi implementation in Eclipse 3.1.2 and the upcoming Eclipse 3.2 fully implement the OSGi R4.0 framework specification.
The OSGi work at Eclipse has returned to its roots in the Equinox project. Please see http://eclipse.org/equinox for more information.