Popfly - with it's Visual Studio integration, ease of creating gadgets and displaying data - looks like the perfect place to create a community of people built around Microsoft technology. Hell, it's obviously not aimed at the mainstream, and the Advanced View to edit modules has some incredible power.
The team says they're working on allowing people to share Windows Forms programs, and I'll bet WPF is easy enough.
I am seriously impressed. It can grab amateurs, and has some features for more advanced users. The social element looks well thought-out and the ability to "Rip" mashups is, well, totally cool.
Gannotti: You've spent too much time working for Microsoft Something like that would be pretty cool though, particularly for Sales folks. It'd be a perfect complementry product to fold into Microsoft Dynamics.