Great insight on the transition and future of OPC-UA from John Weber and Nathan Pocock of Software Toolbox. I hope he's wrong about the slow death of DCOM, but I wouldn't put a wager on it!
OPC-UA vendor perspective from Tom Burke of the OPC Foundation. It's a rather high level vision description of the architecture and commitment of the foundation. You're the man, Tom!
There are other good links. They came from here.