Silverlight's syntax and object model is quite similar to WPF. However, there are some important differences (at least in Beta 1; maybe these differences will disappear in RTM). Today I found another difference concerning the creation of animations in code.

Check out the following WPF code. It works without any problem (it fades in a yellow rectangle):

using System;
using System.Windows;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace WpfApplication1
{
 public partial class Window1 : Window
 {
  public Window1()
  {
   InitializeComponent();
   Create_And_Run_Animation();
  }

  public void Create_And_Run_Animation()
  {
   var storyBoard = new Storyboard();
   var animation = new DoubleAnimation();
   Storyboard.SetTargetName(animation, "Rect");
   Storyboard.SetTargetProperty(animation, new PropertyPath(Rectangle.OpacityProperty));
   animation.To = 1;
   animation.Duration = TimeSpan.FromSeconds(5);
   storyBoard.Children.Add(animation);
   Resources.Add(storyBoard,"sb");
   storyBoard.Begin(this);
  }
 }
}

Note that I call Create_And_Run_Animation in the window's constructor.

If you try the same thing in Silverlight 2.0 Beta 1 it does not work. The rectangle does not fade in:

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media.Animation;

namespace SilverlightApplication1
{
 public partial class Page : UserControl
 {
  public Page()
  {
   InitializeComponent();
   Create_And_Run_Animation();
  }

  public void Create_And_Run_Animation()
  {
   var storyBoard = new Storyboard();
   var animation = new DoubleAnimation();
   Storyboard.SetTargetName(animation, "Rect");
   Storyboard.SetTargetProperty(animation, "Opacity");
   animation.To = 1;
   animation.Duration = TimeSpan.FromSeconds(5);
   storyBoard.Children.Add(animation);
   Resources.Add(storyBoard);
   storyBoard.Begin();
  }
 }
}

However, if you move the call to Create_And_Run_Animation into the handler of the loaded-event everthing works fine:

using [...];

namespace SilverlightApplication1
{
 public partial class Page : UserControl
 {
  public Page()
  {
   InitializeComponent();
   LayoutRoot.Loaded += new RoutedEventHandler(LayoutRoot_Loaded);
  }

  void LayoutRoot_Loaded(object sender, RoutedEventArgs e)
  {
   Create_And_Run_Animation();
  }

  public void Create_And_Run_Animation()
  {
    [...]
  }
 }
}

 I hope this tip will save you some time!