Not specifically Linq related but I was just looking at this:
http://blogs.msdn.com/b/wesdyer/archive/2009/11/18/a-brief-introduction-to-the-reactive-extensions-for-net-rx.aspx
and was intrigued by the alternative approach to drag-and-drop.

Turns out this was a pretty simple example of what the Rx API is capable of. Anyone used this ?