Thanks for the example.  Now let's take it a step further.  When IsButtonEnabled is set to true in the vm, the btn should be enabled.   I'd send this back as a zip but cant see how to do that in this tool.

 <Grid x:Name="LayoutRoot" Background="White" >
        <Grid.Resources>
            <local:IdentityConverter x:Key="IdentityConverter" />
            <local:ViewModel x:Key="vm"/>    
            
        </Grid.Resources>
        <ig:XamRibbon >
            <ig:XamRibbon.Tabs>
                <ig:XamRibbonTabItem>
                    <ig:XamRibbonGroup Caption="group1" >
                        <ig:ButtonTool x:Name="btnButton1" Caption="button1"
                                       IsEnabled="{Binding Source={StaticResource vm}, Path=IsButtonEnabled, Mode=OneWay,
                                                    Converter ={StaticResource IdentityConverter}}"/>
                    </ig:XamRibbonGroup>
                </ig:XamRibbonTabItem>
            </ig:XamRibbon.Tabs>
        </ig:XamRibbon>
        <Button Content="Enable" HorizontalAlignment="Left" Margin="23,159,0,0" VerticalAlignment="Top" Width="75"
                Click="Button_Click"/>

    </Grid>

namespace SilverlightApplication2
{
    public partial class MainPage : UserControl
    {

        private ViewModel viewModel;

        public MainPage()
        {
            InitializeComponent();
            viewModel = new ViewModel();
            this.DataContext = viewModel;
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            viewModel.toggleEnable();
        }


    }

    public class ViewModel : INotifyPropertyChanged
    {      

        private bool _IsButtonEnabled;
        public bool IsButtonEnabled
        {
            get { return _IsButtonEnabled; }
            set
            {
                if (_IsButtonEnabled != value)
                {
                    _IsButtonEnabled = value;
                    NotifyPropertyChanged("IsButtonEnabled");
                }
            }
        }

        public ViewModel()
        {
            IsButtonEnabled = false;
        }

        public void toggleEnable()
        {
            if (IsButtonEnabled)
            {
                IsButtonEnabled = false;
            }
            else
            {
                IsButtonEnabled = true;
            }
            
        }

        public event PropertyChangedEventHandler PropertyChanged;
        protected void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }

}

I cant for the life of me get the PropertyChanged event to fire.