During a discussion on the recent controversy surrounding SodaStream, the idea was brought up that the premise of Israelis and Palestinians working together in the same factory for the same wages might actually help foster peace in the West Bank region.
To answer this, I tried looking back through my basic knowledge of history to see if something like this ever happened in the past, but I couldn't come up with anything. After all, industry and capitalism as we know it is only, what, 200 years old? That can't be much time to set a historical precedent.
That said, I want to see if maybe there's something I missed, and two peoples who had years' worth of bloody conflict behind them did, at one point, punch the same clock and earn the same wages together.
One example is the Kaesong Plant, between North and South Korea. It hasn't necessarily stopped their fighting, but people there have worked together as you said. The intention of it is for eventual reunification, and this was a test case to get people to see it was possible supposedly. Hasn't happened, but the intent is there.
I don't know any other examples off the top of my head, though. You're right in that it's not exactly something that happened much recently.