I don't think image animation is supported. You can submit a feature request for this: http://devcenter.infragistics.com/Protected/RequestFeature.aspx.  You can also work around this with the following code in your Form:

private void OnAnimateImage( object sender, EventArgs args )
{
 if ( this.IsHandleCreated && this.InvokeRequired )
 {
  this.BeginInvoke( new EventHandler( this.OnAnimateImage ), (Image)sender );
 }
 else
 {
  UIElement controlElement = ( (IUltraControlElement)this._Form1_Toolbars_Dock_Area_Top ).MainUIElement;
  UIElement buttonElement = controlElement.GetDescendant( typeof( ApplicationMenuButtonUIElement ) );

  if ( buttonElement != null )
   buttonElement.Invalidate();
 }
}

private void Form1_Load( object sender, EventArgs e )
{
 this._Form1_Toolbars_Dock_Area_Top.Paint += new PaintEventHandler( _Form1_Toolbars_Dock_Area_Top_Paint );
 ImageAnimator.Animate( (Image)this.ultraToolbarsManager1.Ribbon.ApplicationMenuButtonImage, new EventHandler( this.OnAnimateImage ) );
}

private void Form1_FormClosed( object sender, FormClosedEventArgs e )
{
 ImageAnimator.StopAnimate( (Image)this.ultraToolbarsManager1.Ribbon.ApplicationMenuButtonImage, new EventHandler( this.OnAnimateImage ) );
}

private void _Form1_Toolbars_Dock_Area_Top_Paint( object sender, PaintEventArgs e )
{
 ImageAnimator.UpdateFrames();
}