Hello
I am proud to present the first free OPC Server for Arduino. You can get more information from the Arduino OPC Server project page at:
http://www.ismsolar.com/arduino-opc-server
Now it is in beta stage so help is wanted to debug. The project is going to be Open Source and source will be published as soon as stable version will be released with your help (of course if you need the sources now you can contact with me).
If you use it please, tell me about that to improve it.
There is a forum of the project if you need some open support.
All the best
ilde