This is the full output including the warnings:

** (Banshee:7035): WARNING **: The following assembly referenced from /usr/lib/banshee-1/Extensions/Banshee.AppIndicator.dll could not be loaded:
     Assembly:   appindicator-sharp    (assemblyref_index=8)
     Version:    0.0.0.0
     Public Key: bcae265d1c7ab4c2
The assembly was not found in the Global Assembly Cache, a path listed in the MONO_PATH environment variable, or in the location of the executing assembly (/usr/lib/banshee-1/Extensions/).


** (Banshee:7035): WARNING **: Could not load file or assembly 'appindicator-sharp, Version=0.0.0.0, Culture=neutral, PublicKeyToken=bcae265d1c7ab4c2' or one of its dependencies.
[Warn  11:01:21.556] Caught an exception - System.TypeLoadException: Could not load type 'Banshee.AppIndicator.AppIndicatorService' from assembly 'Banshee.AppIndicator, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null'. (in `mscorlib')
  at (wrapper managed-to-native) System.MonoType:GetConstructors_internal (System.Reflection.BindingFlags,System.Type)
  at System.MonoType.GetConstructors (BindingFlags bindingAttr) [0x00000] 
  at System.MonoType.GetConstructorImpl (BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) [0x00000] 
  at System.Type.GetConstructor (BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) [0x00000] 
  at System.Activator.CreateInstance (System.Type type, Boolean nonPublic) [0x00000] 
  at System.Activator.CreateInstance (System.Type type) [0x00000] 
  at Mono.Addins.TypeExtensionNode.CreateInstance () [0x00000] 
  at Mono.Addins.InstanceExtensionNode.CreateInstance (System.Type expectedType) [0x00000] 
  at Banshee.ServiceStack.ServiceManager.StartExtension (Mono.Addins.TypeExtensionNode node) [0x00000] 
[Warn  11:01:21.556] Extension `/Banshee/ServiceManager/Service/__nid_14' not started: Could not load type 'Banshee.AppIndicator.AppIndicatorService' from assembly 'Banshee.AppIndicator, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null'.
[Warn  11:01:21.556] Caught an exception - System.TypeLoadException: Could not load type 'Banshee.AppIndicator.AppIndicatorService' from assembly 'Banshee.AppIndicator, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null'. (in `mscorlib')
  at (wrapper managed-to-native) System.MonoType:GetConstructors_internal (System.Reflection.BindingFlags,System.Type)
  at System.MonoType.GetConstructors (BindingFlags bindingAttr) [0x00000] 
  at System.MonoType.GetConstructorImpl (BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) [0x00000] 
  at System.Type.GetConstructor (BindingFlags bindingAttr, System.Reflection.Binder binder, CallingConventions callConvention, System.Type[] types, System.Reflection.ParameterModifier[] modifiers) [0x00000] 
  at System.Activator.CreateInstance (System.Type type, Boolean nonPublic) [0x00000] 
  at System.Activator.CreateInstance (System.Type type) [0x00000] 
  at Mono.Addins.TypeExtensionNode.CreateInstance () [0x00000] 
  at Mono.Addins.InstanceExtensionNode.CreateInstance (System.Type expectedType) [0x00000] 
  at Banshee.ServiceStack.ServiceManager.StartExtension (Mono.Addins.TypeExtensionNode node) [0x00000] 
[Warn  11:01:21.556] Extension `/Banshee/ServiceManager/Service/__nid_14' not started: Could not load type 'Banshee.AppIndicator.AppIndicatorService' from assembly 'Banshee.AppIndicator, Version=1.6.0.0, Culture=neutral, PublicKeyToken=null'.