Resource lookup in Geronimo 3.0 returns "bundle" type of urls. However, a lot of Geronimo code and a number of third party libraries assumes that urls returned by resource lookup return "jar" or "file" type of urls. Because of this difference a lot of applications might not work properly on Geronimo 3.0. The Geronimo specific code has mostly been updated to use OSGi-friendly ways to look for resources. However, we can't expect every 3rd party library to be updated to be OSGi friendly. So we might need a solution that can return "jar" or "file" urls that works with most libraries.
One possible solution is to use the BundleResourceClassLoader in the xbean-bundleutils project (currently used in the OpenJPA plugin). That solution could be enhanced with Equinox-specific extension (URLConverter service) that can convert "bundle" urls directly into "jar" or "file" urls (using the jars in its bundle cache).