We are a small software company, and I know that some customers of us are interested in OPC on Linux in the past. There is one working solution as far as I know. It is a OPC Toolkit from Technotrend which is based on the COM/DCOM implementation EntireX of Software AG. But its not Open Source unfortunally.
It wouldn't be. The Software AG implementation was produced under contract from Microsoft back when they thought DCOM was going to rule the world, and it's based on the Windows NT codebase. In fact they did a mini-wine and duplicated parts of the win32 API in order to make it work.
