Johan you are absolutely correct and we took the first steps to use the NetTopologySuite today. Kinnon has already done a silverlight port as he mentioned in our futures thread:
I'm in the process of giving him want he needs to move ahead here.
The last we want to do is reinvent the wheel, there are so many other cool things for us to spend our time on.
Love to know your thoughts on how best to get the silverlight port integrated - should we host the port here, talk to the NetTopology guys and see if they want to host/support it?
The next steps to actually make the suite useful is to provide vector rendering of all the geometries in Silverlight. We will no doubt need a hand.