We haven’t even begun to see the power of WPF/E(Silverlight) applications. Wpfe is still in infancy (not even in beta release) and programmers are making their first exploratory applications. Trying ideas out before buying into that new technology.
Much of the web communities attention is focused on AJAX, which is changing the way we think about web UI. There are 100+ AJAX frameworks in active development and companies all over the world trying to see how far they can stretch the AJAX model.
I think WPF/e is another technology that will change the way we perceive web UI.
Here is a little WPF/e experiment from Marc for you to check out. It layers WPF controls, stickpins and images over the virtual earth maps.