In JDK 6 b95 there are two build problems in the deploy makefiles:

        /bin/cp: cannot stat
          `/usr/local/java/jdk1.5.0_06/jre/plugin/i386/ns7-gcc29/ns7/libjavaplugin_oji.so':
          No such file or directory
            To fix it, apply the following patch to the file
            deploy/make/plugin/adapter/oji-gcc29-adapter/Makefile:
            26c26
            < $(CP) $(ALT_GCC29_PLUGIN_LIB_PATH)/ns7/lib$(LIBRARY).so \
            ---
            > $(CP) $(ALT_GCC29_PLUGIN_LIB_PATH)/lib$(LIBRARY).so \

        /bin/cp: cannot stat
           `/usr/local/java/jdk1.5.0_06/jre/plugin/i386/ns7-gcc29/libjavaplugin_nscp_gcc29.so':
            No such file or directory
            To fix it, comment out lines 23-24 in file
            deploy/make/plugin/nscore/linux-gcc29/Makefile

See http://blogs.sun.com/roller/page/navi?entry=try_this_at_home_building for details.