One of the reasons I love working in the developer platform space is that I get to see the amazing solutions people build with our product.
I am very impressed with what the Popfly team has been able to create on top of Silverlight 1.1 Alpha in just a few weeks... Not only is it a cool app that is addictive to play with, but it shows what is possible with Silverlight 1.1.. Between it and TopBanna I think we are starting to get a peak at what is to come on the web.
Here is what I came up with with literally 5 mins of playing around with it.. Notice how it reuses a block someone else published, cool and viral!
Check on JohnMont's post for some great info and links.