Index: src/Util/LogicalThreadContextProperties.cs
===================================================================
--- src/Util/LogicalThreadContextProperties.cs	(revision 480010)
+++ src/Util/LogicalThreadContextProperties.cs	(working copy)
@@ -96,9 +96,25 @@
 				return null;
 			}
 			set 
-			{ 
+			{
 				// Force the dictionary to be created
-				GetProperties(true)[key] = value; 
+				PropertiesDictionary dictionary = GetProperties(true);
+
+				// If there is already a value set for this key and it
+				// is different from the value to be set then we
+				// must create a shallow copy of the dictionary to
+				// propagate an independent dictionary with the new value
+				// through the execution code path.
+				if (dictionary[key] != null && dictionary[key] != value)
+				{
+					dictionary = dictionary.Clone() as PropertiesDictionary;
+					dictionary[key] = value;
+					CallContext.SetData("log4net.Util.LogicalThreadContextProperties", dictionary);
+				}
+				else
+				{
+					dictionary[key] = value;
+				}
 			}
 		}
 
Index: src/Util/PropertiesDictionary.cs
===================================================================
--- src/Util/PropertiesDictionary.cs	(revision 480010)
+++ src/Util/PropertiesDictionary.cs	(working copy)
@@ -21,6 +21,7 @@
 #if !NETCF
 using System.Runtime.Serialization;
 using System.Xml;
+using System.Runtime.Remoting.Messaging;
 #endif
 
 namespace log4net.Util
@@ -34,13 +35,25 @@
 	/// objects that are serializable will
 	/// be serialized along with this collection.
 	/// </para>
+	/// <para>
+	/// Christian Kihm:
+	/// 
+	/// MSDN says that ILogicalThreadAffinative marks an object that can 
+	/// propagate outside of an AppDomain in a LogicalCallContext. I have made
+	/// the experience that you also have to mark an object with 
+	/// ILogicalThreadAffinative to propagate it outside of the current Thread.
+	/// 
+	/// To get LogicalThreadContextProperties to work as expected we must 
+	/// implement ILogicalThreadAffinative.
+	/// </para>
 	/// </remarks>
 	/// <author>Nicko Cadell</author>
 	/// <author>Gert Driesen</author>
 #if NETCF
 	public sealed class PropertiesDictionary : ReadOnlyPropertiesDictionary, IDictionary
 #else
-	[Serializable] public sealed class PropertiesDictionary : ReadOnlyPropertiesDictionary, ISerializable, IDictionary
+	[Serializable]
+	public sealed class PropertiesDictionary : ReadOnlyPropertiesDictionary, ISerializable, IDictionary, ILogicalThreadAffinative, ICloneable
 #endif
 	{
 		#region Public Instance Constructors
@@ -329,6 +342,18 @@
 		}
 
 		#endregion
+
+		#region ICloneable Members
+
+		/// <summary>
+		/// Create a shallow copy
+		/// </summary>
+		/// <returns>A shallow copy</returns>
+		public object Clone()
+		{
+			return new PropertiesDictionary(new ReadOnlyPropertiesDictionary(this));
+		}
+
+		#endregion
 	}
-}
-
+}
\ No newline at end of file