Description of problem:

Going into a desktop session generated the following:

Process /usr/bin/gnome-power-manager was killed by signal 11 (SIGSEGV)

A look into a dropped core file shows this:

Core was generated by `gnome-power-manager'.
Program terminated with signal 11, Segmentation fault.
#0  0x00000038d9ca0f1a in g_dbus_error_encode_gerror ()
   from /lib64/libgio-2.0.so.0
(gdb) where
#0  0x00000038d9ca0f1a in g_dbus_error_encode_gerror ()
   from /lib64/libgio-2.0.so.0
#1  0x00000038d9cba00d in g_dbus_method_invocation_return_gerror ()
   from /lib64/libgio-2.0.so.0
#2  0x000000000040ad51 in gpm_backlight_dbus_method_call (
    connection=<optimized out>, sender=<optimized out>, 
    object_path=<optimized out>, interface_name=<optimized out>, method_name=
    0x7f72a4004550 "GetBrightness", parameters=0x7f72a4008800, invocation=
    0x7f72a4003060, user_data=0x1eff960) at gpm-backlight.c:699
#3  0x00000038d9ca5fd0 in ?? () from /lib64/libgio-2.0.so.0
#4  0x00000038d5842a9d in g_main_context_dispatch ()
   from /lib64/libglib-2.0.so.0
#5  0x00000038d5843278 in ?? () from /lib64/libglib-2.0.so.0
#6  0x00000038d58438ba in g_main_loop_run () from /lib64/libglib-2.0.so.0
#7  0x0000000000408476 in main (argc=1, argv=0x7fff48ca4838) at gpm-main.c:304
(gdb) f 2
#2  0x000000000040ad51 in gpm_backlight_dbus_method_call (
    connection=<optimized out>, sender=<optimized out>, 
    object_path=<optimized out>, interface_name=<optimized out>, method_name=
    0x7f72a4004550 "GetBrightness", parameters=0x7f72a4008800, invocation=
    0x7f72a4003060, user_data=0x1eff960) at gpm-backlight.c:699
699                             g_dbus_method_invocation_return_gerror (invocation, error);
(gdb) l
694             }
695             if (g_strcmp0 (method_name, "SetBrightness") == 0) {
696                     g_variant_get (parameters, "(u)", &value);
697                     ret = gpm_backlight_set_brightness (backlight, value, &error);
698                     if (!ret) {
699                             g_dbus_method_invocation_return_gerror (invocation, error);
700                             g_error_free (error);
701                     } else {
702                             g_dbus_method_invocation_return_value (invocation, NULL);
703                     }

What a value of '*invocation' may be I cannot tell as gdb responds to all attempts with "<incomplete type>".  OTOH '*error' prints as
'{domain = 0, code = 0, message = 0x0}'.  An attempt to access such 'message' would account for SIGSEGV.

Version-Release number of selected component (if applicable):
gnome-power-manager-2.91.5-4.fc15.x86_64

How reproducible:
No idea. Found that after some wanderings "in blind" attempting to figure out anything in a desktop session which looks like in attachment 479724 [details] to bug 678803.

Hard to tell for me how much sense "SetBrightness" and 'backlight' make in the context.  This is a desktop machine with a standalone LCD monitor.

Additional info:
See bug 678803 for a short video hardware description.