I discuss Silverlight (v4 onwards) as a possible platform for a program that requires direct interaction between two instances. As far as I can tell, this is still not possible with SL-socket assumptions for client-server comms.
Suppose this is for a highly interactive two-player game, and you will have a good idea of the performance requirements.
You don’t need to scale thousands of users with the same server, so the performance and scaling problems that concern most people do not matter.
This answer seems rather negative.
However, there is the possibility of installing a communication kernel on desktop computers for people who need commits, so I am thinking about the possibility of having a small binary local server that processes true peer messages and talks using the local SL client.
That sounds a bit like Skinkins did for the video , and the only problem would be duplicate messaging, but it is not much more than acting as a router.
UPDATE
Thinking more about Michael, it occurred to me that my particular scenario was probably satisfied with two SL instances communicating on the same machine - inter-process comms.
Ironically, this is possible with the SL browser , but I'm afraid with OOB.