Thanks Pedro.

I just built f-spot from git, but the error stays the same. It still crashes instantly when I try to export pictures to Facebook ...

Once more, here is what f-spot --debug shows up with when I click Picture -> Export -> Facebook

Marshaling activate signal
Exception in Gtk# callback delegate
  Note: Applications can use GLib.ExceptionManager.UnhandledException to handle the exception.
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> GLib.GException: Doppelte Objektkennung »label6« in Zeile 505 (zuvor in Zeile 80)
  at GtkBeans.Builder.AddFromString (System.String buffer) [0x00000]
  at GtkBeans.Builder..ctor (System.Reflection.Assembly assembly, System.String resource_name, System.String translation_domain) [0x00000]
  at FSpot.UI.Dialog.BuilderDialog..ctor (System.Reflection.Assembly assembly, System.String resourceName, System.String dialogName) [0x00000] in /home/frank/tmp/f-spot/src/BlockProcessor.cs:1
  at FSpot.Exporter.Facebook.FacebookExportDialog..ctor (IBrowsableCollection selection) [0x00000]
  at FSpot.Exporter.Facebook.FacebookExport.Run (IBrowsableCollection selection) [0x00000]
  at FSpot.Extensions.ExportMenuItemNode.OnActivated (System.Object o, System.EventArgs e) [0x00017] in /home/frank/tmp/f-spot/src/Extensions/ExportMenuItemNode.cs:30
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000]
  --- End of inner exception stack trace ---
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000]
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000]
  at System.Delegate.DynamicInvokeImpl (System.Object[] args) [0x00000]
  at System.MulticastDelegate.DynamicInvokeImpl (System.Object[] args) [0x00000]
  at System.Delegate.DynamicInvoke (System.Object[] args) [0x00000]
  at GLib.Signal.ClosureInvokedCB (System.Object o, GLib.ClosureInvokedArgs args) [0x00000]
  at GLib.SignalClosure.Invoke (GLib.ClosureInvokedArgs args) [0x00000]
  at GLib.SignalClosure.MarshalCallback (IntPtr raw_closure, IntPtr return_val, UInt32 n_param_vals, IntPtr param_values, IntPtr invocation_hint, IntPtr marshal_data) [0x00000]
   at GLib.ExceptionManager.RaiseUnhandledException(System.Exception e, Boolean is_terminal)
   at GLib.SignalClosure.MarshalCallback(IntPtr raw_closure, IntPtr return_val, UInt32 n_param_vals, IntPtr param_values, IntPtr invocation_hint, IntPtr marshal_data)
   at Gtk.Application.gtk_main()
   at Gtk.Application.Run()
   at FSpot.Driver.Main(System.String[] args) in /home/frank/tmp/f-spot/src/main.cs:line 345
[Debug 14:35:39.997] Finalizer called on FSpot.Category. Should be Disposed
[Debug 14:35:39.998] Finalizer called on FSpot.Category. Should be Disposed
[Debug 14:35:39.998] Finalizer called on FSpot.Category. Should be Disposed
[Debug 14:35:39.998] Finalizer called on FSpot.Category. Should be Disposed
[Debug 14:35:39.998] Finalizer called on FSpot.Category. Should be Disposed
[Debug 14:35:39.998] Finalizer called on FSpot.Widgets.Filmstrip. Should be Disposed