Checking out Planet Eclipse Glyn Normington has a very nice write-up about Eclipse Virgo – the OSGI based web server.

This nested framework approach also enables applications to use new versions of the Spring framework (regardless of the fact the kernel depends on Spring 3.0.0). All the major Java EE application servers are now built on top of OSGi, but only Virgo was designed for OSGi and didn’t need OSGi to be retrofitted.

Referenced article is here.