WPF comes with great support for animation using XAML without needing to code this in for example C#. With Silverlight (fka "WPF/E") you can also do animations from XAML. If you want to perform custom animations in code that you can't do using XAML, you...
If you haven't heard the news yet, you must be living under a rock ;) There is a new CLR in town. Silverlight (fka "WPF/E") 1.1 comes with its own CLR. And the best news is that it runs both on the Mac and the PC. Go check it out at silverlight.net ....