There are products produced in Europe that have an OU for a basic business
reason: in America we won't know who the European Kosher supervising
organization is. So a company that wants to market in the US has to get an
OU to sell. What the OU will do is jointly establish guidelines with the
European organization and jointly decide on a Mashgeach(supervisor). A
friend of mine in Israel told me he was employed as the machgiach for 3
organizations that were giving a hecsher(kosher certification) on a product.
Dovid