Silverlight / WPF

        private ErrorStatus _errorStatus;
        public ErrorStatus ErrorStatus
        {
            get { return _errorStatus; }
            set
            {
                if (_errorStatus != value)
                {
                    _errorStatus = value;
                    RaisePropertyChanged("ErrorStatus");
                }
            }
        }

MyService.PropertyChanged += MyService_PropertyChanged;

private void MyService_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
            switch (e.PropertyName)
            {
                case "ServiceStatus":
                    ErrorStatus = MyService.ServiceStatus;
                    break;
            }
}