You can submit a feature request for this here: http://devcenter.infragistics.com/Protected/RequestFeature.aspx.

As a workaround, you can use the following code:

private void OnAnimateImage( object sender, EventArgs args )
{
 if ( this.ultraTabControl1.IsHandleCreated &&
  this.ultraTabControl1.InvokeRequired )
 {
  this.ultraTabControl1.BeginInvoke( new EventHandler( this.OnAnimateImage ), (Image)sender );
 }
 else
 {
  foreach ( UltraTab tab in this.ultraTabControl1.Tabs )
  {
   if ( tab.Appearance.Image != sender )
    continue;

   if ( this.ultraTabControl1.UIElement != null )
   {
    UIElement element = this.ultraTabControl1.UIElement.GetDescendant( typeof( TabItemUIElement ), tab );

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

   break;
  }
 }
}

private void Form1_Load( object sender, EventArgs e )
{
 this.ultraTabControl1.Paint += new System.Windows.Forms.PaintEventHandler( this.ultraTabControl1_Paint );
 ImageAnimator.Animate( (Image)this.ultraTabControl1.Tabs[ 0 ].Appearance.Image, new EventHandler( this.OnAnimateImage ) );
}

private void Form1_FormClosed( object sender, FormClosedEventArgs e )
{
 ImageAnimator.StopAnimate( (Image)this.ultraTabControl1.Tabs[ 0 ].Appearance.Image, new EventHandler( this.OnAnimateImage ) );
}

private void ultraTabControl1_Paint( object sender, PaintEventArgs e )
{
 ImageAnimator.UpdateFrames();
}