In the git sources for dbus-python I downloaded two days ago (I haven't figured out how to re-sync yet), if you attempt to connect to the SystemBus without importing dbus.glib, the program crashes.  A quick demo: >>> import dbus >>> bus=dbus.SystemBus() process 24616: arguments to dbus_connection_close() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file dbus-connection.c line 2740. This is normally a bug in some application using the D-Bus library.   /usr/lib/libdbus-1.so.3 [0xb7b0c77d]   /usr/lib/libdbus-1.so.3 [0xb7b08637]   /usr/lib/libdbus-1.so.3 [0xb7afd0c6]   /usr/lib/libdbus-1.so.3(dbus_connection_close+0xd1) [0xb7ad86c1]   /usr/lib/python2.4/site-packages/_dbus_bindings.so [0xb7b588b8]   /usr/lib/python2.4/site-packages/_dbus_bindings.so [0xb7b57761]   /usr/lib/libpython2.4.so.1.0 [0xb7ea7efb]   /usr/lib/libpython2.4.so.1.0(PyCFunction_Call+0xf2) [0xb7e94042]   /usr/lib/libpython2.4.so.1.0(PyObject_Call+0x37) [0xb7e6f467]   /usr/lib/libpython2.4.so.1.0(PyEval_EvalFrame+0x2bfe) [0xb7eca2ce]   /usr/lib/libpython2.4.so.1.0(PyEval_EvalCodeEx+0x5f5) [0xb7eccbc5]   /usr/lib/libpython2.4.so.1.0(PyEval_EvalFrame+0x449e) [0xb7ecbb6e]   /usr/lib/libpython2.4.so.1.0(PyEval_EvalCodeEx+0x5f5) [0xb7eccbc5]   /usr/lib/libpython2.4.so.1.0 [0xb7e8488c]   /usr/lib/libpython2.4.so.1.0(PyObject_Call+0x37) [0xb7e6f467]   /usr/lib/libpython2.4.so.1.0 [0xb7eab84c]   /usr/lib/libpython2.4.so.1.0 [0xb7ea4c22]   /usr/lib/libpython2.4.so.1.0(PyObject_Call+0x37) [0xb7e6f467]   /usr/lib/libpython2.4.so.1.0(PyEval_EvalFrame+0x2bfe) [0xb7eca2ce]   /usr/lib/libpython2.4.so.1.0(PyEval_EvalCodeEx+0x5f5) [0xb7eccbc5]   /usr/lib/libpython2.4.so.1.0(PyEval_EvalCode+0x63) [0xb7ecce43]   /usr/lib/libpython2.4.so.1.0 [0xb7ee7745]   /usr/lib/libpython2.4.so.1.0(PyRun_InteractiveOneFlags+0x17f) [0xb7ee8eaf]   /usr/lib/libpython2.4.so.1.0(PyRun_InteractiveLoopFlags+0x5b) [0xb7ee902b]   /usr/lib/libpython2.4.so.1.0(PyRun_AnyFileExFlags+0x4e) [0xb7ee95fe]   /usr/lib/libpython2.4.so.1.0(Py_Main+0xae8) [0xb7eef848]   python(main+0x2a) [0x804860a]   /lib/libc.so.6(__libc_start_main+0xe6) [0xb7d05896]   python [0x8048541] Aborted On the other hand, if you do import dbus and then dbus.glib, it works fine.  It's a small bug, but probably worth fixing :)