MefControllerFactory.cs

	public class MefControllerFactory : IControllerFactory
	{
		private readonly WebScopedContainerManager _containerManager;

		public MefControllerFactory(WebScopedContainerManager containerManager)
		{
			_containerManager = containerManager;
		}

		#region IControllerFactory Members

		public IController CreateController(RequestContext requestContext, string controllerName)
		{
			string version = requestContext.RouteData.Values["version"].ToString();
			var container = _containerManager.GetRequestContainer(requestContext.HttpContext.Items);
			var controllers = container.GetExports<IController, IDictionary<string, object>>();

			controllers = controllers
				.Where(exp =>
					exp.Metadata.ContainsKey(Constants.MetaControllerName)
					&& String.Equals(exp.Metadata[Constants.MetaControllerName].ToString(), controllerName, StringComparison.InvariantCultureIgnoreCase))
				.Where(exp =>
					exp.Metadata.ContainsKey(Constants.MetaControllerName)
					&& String.Equals(exp.Metadata[Constants.MetaApiVersion].ToString(), version, StringComparison.InvariantCultureIgnoreCase));

			var controllerExport = controllers.FirstOrDefault();

			if (controllerExport == null)
				return null;

			return controllerExport.Value;
		}

		public void ReleaseController(IController controller)
		{
		}

		#endregion
	}

nice and clean Job, thank you :)