Update:
List of classes still required as of 8th June 2006:
java/awt/MenuContainer java/awt/Panel java/awt/datatransfer/DataFlavor java/awt/datatransfer/Transferable java/awt/datatransfer/UnsupportedFlavorException java/awt/image/ImageObserver javax/accessibility/Accessible javax/rmi/CORBA/Util javax/rmi/CORBA/UtilDelegate javax/rmi/PortableRemoteObject org/omg/CORBA/BAD_PARAM org/omg/CORBA/CompletionStatus org/omg/CORBA/INITIALIZE org/omg/CORBA/INTERNAL org/omg/CORBA/INVALID_TRANSACTION org/omg/CORBA/MARSHAL org/omg/CORBA/ORB org/omg/CORBA/Object org/omg/CORBA/SystemException org/omg/CORBA/UserException org/omg/CORBA/portable/IDLEntity org/omg/IOP/CodecPackage/FormatMismatch org/omg/IOP/CodecPackage/TypeMismatch org/omg/PortableInterceptor/RequestInfo org/omg/PortableInterceptor/RequestInfoOperations org/omg/PortableInterceptor/ServerRequestInfo org/omg/PortableInterceptor/ServerRequestInfoOperations org/omg/PortableServer/POA org/omg/PortableServer/POAManagerPackage/AdapterInactive org/omg/PortableServer/POAOperations
I generated a list of required classes for Apache Geronimo by taking geronimo-jetty-j2ee-1.0.tar.gz and running it with:
java -verbose:class -jar bin/server.jar
Using a browser, I then click most of the links on the interface pages - enabling jetty statistics and starting the sample application.
I then compared the resulting list of 606 JRE classes against those found in the jars generated by a build of Classlib r386322. 495 classes were found. The list of classes still required are:
java/awt/Component java/awt/Container java/awt/Image java/awt/MenuContainer java/awt/Panel java/awt/datatransfer/DataFlavor java/awt/datatransfer/Transferable java/awt/datatransfer/UnsupportedFlavorException java/awt/image/ImageObserver java/beans/BeanDescriptor java/beans/BeanInfo java/beans/EventSetDescriptor java/beans/FeatureDescriptor java/beans/IndexedPropertyDescriptor java/beans/IntrospectionException java/beans/Introspector java/beans/MethodDescriptor java/beans/PropertyChangeEvent java/beans/PropertyChangeSupport java/beans/PropertyDescriptor java/beans/PropertyEditor java/beans/PropertyEditorManager java/beans/PropertyEditorSupport java/beans/PropertyVetoException java/beans/SimpleBeanInfo java/nio/channels/ServerSocketChannel java/nio/channels/spi/AbstractSelectionKey java/rmi/AccessException java/rmi/AlreadyBoundException java/rmi/MarshalException java/rmi/MarshalledObject java/rmi/NoSuchObjectException java/rmi/NotBoundException java/rmi/Remote java/rmi/RemoteException java/rmi/UnexpectedException java/rmi/activation/ActivationDesc java/rmi/activation/ActivationException java/rmi/activation/ActivationGroupDesc java/rmi/activation/ActivationGroupID java/rmi/activation/ActivationID java/rmi/activation/ActivationInstantiator java/rmi/activation/ActivationMonitor java/rmi/activation/ActivationSystem java/rmi/activation/UnknownGroupException java/rmi/activation/UnknownObjectException java/rmi/dgc/DGC java/rmi/dgc/Lease java/rmi/dgc/VMID java/rmi/registry/LocateRegistry java/rmi/registry/Registry java/rmi/server/LogStream java/rmi/server/ObjID java/rmi/server/Operation java/rmi/server/RMIClassLoader java/rmi/server/RMIClassLoaderSpi java/rmi/server/RMIClientSocketFactory java/rmi/server/RMIServerSocketFactory java/rmi/server/RMISocketFactory java/rmi/server/RemoteCall java/rmi/server/RemoteObject java/rmi/server/RemoteRef java/rmi/server/RemoteServer java/rmi/server/RemoteStub java/rmi/server/ServerRef java/rmi/server/Skeleton java/rmi/server/SkeletonNotFoundException java/rmi/server/UID java/rmi/server/UnicastRemoteObject java/util/logging/ErrorManager java/util/logging/Formatter java/util/logging/Handler java/util/logging/Level java/util/logging/LogManager java/util/logging/Logger java/util/logging/LoggingPermission java/util/logging/SimpleFormatter java/util/logging/StreamHandler javax/accessibility/Accessible javax/crypto/Mac javax/crypto/MacSpi javax/crypto/SecretKey javax/crypto/spec/RC2ParameterSpec javax/crypto/spec/RC5ParameterSpec javax/crypto/spec/SecretKeySpec javax/rmi/CORBA/Util javax/rmi/CORBA/UtilDelegate javax/rmi/PortableRemoteObject javax/transaction/InvalidTransactionException javax/transaction/TransactionRequiredException javax/transaction/TransactionRolledbackException org/omg/CORBA/BAD_PARAM org/omg/CORBA/CompletionStatus org/omg/CORBA/INITIALIZE org/omg/CORBA/INTERNAL org/omg/CORBA/INVALID_TRANSACTION org/omg/CORBA/MARSHAL org/omg/CORBA/ORB org/omg/CORBA/Object org/omg/CORBA/SystemException org/omg/CORBA/UserException org/omg/CORBA/portable/IDLEntity org/omg/IOP/CodecPackage/FormatMismatch org/omg/IOP/CodecPackage/TypeMismatch org/omg/PortableInterceptor/RequestInfo org/omg/PortableInterceptor/RequestInfoOperations org/omg/PortableInterceptor/ServerRequestInfo org/omg/PortableInterceptor/ServerRequestInfoOperations org/omg/PortableServer/POA org/omg/PortableServer/POAManagerPackage/AdapterInactive org/omg/PortableServer/POAOperations