For those who didn't catch the news at Digitalbond Eric Byres has formed Byres Security.
I first crossed paths with Eric when we were both included in an article by Kevin Poulsen when he was at Security Focus (Kevin is at WIRED now) several years ago. It was one of the first times the mainstream information security press addressed the issues with control systems. I didn't get a chance to meet him face to face until just last year. He is just as affable in person as he is on the phone and as his written work would suggest.
Eric has been at the lead of the SCADA security topic for years now. He and PA Consulting were two of the front runners in providing services for DCS and SCADA security. Along with Darren (one of other members of Byres Security) they have perhaps the best technical and conceptual understanding of the issues and potential solutions out there.
They have created an appliance - Tofino - that can be used to protect the PCN with minimal or no interference.