I have been doing some research and wanted everyone to know the difference between these products, sure, you could just google it but I thought i'll just sum it all up here ;).
I am a firm believer in user experience and if you are developing an application/product, why not just make it nice too, so that the user doesn't get bored with what they have to work on all day and sometimes all night.
With the new products being released, it makes it so much easier to have the artist /graphic designer on a team , express themselves and let their creative juices flow.
WPF : The new presentation technology in .NET3.0 which uses the Direct3D rendering engine. This is awesome as it takes advantage of your graphics hardware (e.g. NVIDIA 8800). This means that is that it's fast and we all want fast and performant applications.
SilverLight (WPF/E) : Cross platform WPF basically
Expression Blend : This is just an awesome package/product from Microsoft, built using WPF. This package provides an awesome but easy to use interface designer.
These are all exciting packages and I cannot wait to continue playing with it.
Stay tuned for some awesome screenshots.