Microsoft are about to release their new browser plugin Silverlight, which will offer a rich user experience for users that is far beyond anything we experience at the moment. Scott Guthrie is one of the people involved in the development of silverlight and offers a comprehensive view of it on his blog:
http://weblogs.asp.net/scottgu/archive/2007/05/07/silverlight.aspx
Silverlight opens up a lot of opportunities to build significantly richer client experiences that run cross platform and cross browser. For .NET developers, it means that you can now write .NET code using any development language (VB, C#, Javascript, Python, Ruby and more), so you don't need to get bogged down with javascript, but it is there if you want it. Silverlight works with a subset of WPF, so the expression toolset can be used for building the UI.
Developers can download the following poster, to give them an idea of namespaces and features.
Finally, for anyone wanting to write a silverlight application, we have found the following demo a good starting point:
Analogue Clock