Easiest way to have a program minimize itself to the system tray using .NET 4

Example in MSDN forum

Here’s a quick example to show how to minimize to the notification area. You need to add references to the System.Window.Forms and System.Drawing assemblies.

public partial class Window1 : System.Windows.Window
{

    public Window1()
    {
        InitializeComponent();

        System.Windows.Forms.NotifyIcon ni = new System.Windows.Forms.NotifyIcon();
        ni.Icon = new System.Drawing.Icon("Main.ico");
        ni.Visible = true;
        ni.DoubleClick += 
            delegate(object sender, EventArgs args)
            {
                this.Show();
                this.WindowState = WindowState.Normal;
            };
    }

    protected override void OnStateChanged(EventArgs e)
    {
        if (WindowState == System.Windows.WindowState.Minimized)
            this.Hide();

        base.OnStateChanged(e);
    }
}