I did a presentation recently at the NxtGenUG in Oxford, where I introduced WPF and WCF in a combined session. I created a network enabled implementation of Connect Four to do this. Here's the download of the demo solution, as requested by some of the attendees:

  ConnectFour.zip (30668 bytes)

If you missed my presentation in Oxford, I suggest you keep an eye on the DDD 5 agenda voting page. I submitted the same session there and as soon as their voting opens, you can vote for the same session there and come see it at DDD 5 - assuming it gets selected, of course :-)