We have currently 3 magento stores. 2 empty stores, and 1 store populated with 40 products. I found out a bit too late about openerp, but I want to have installed open erp on our server, and be it connected with the 3 magento stores. What we need is that orders from the 3 websites automatically enter in openerp, and if possibile as well that some basic fields can be handled from openerp, and can be uploaded to magento. (Basically only the prices on the site, and the product codes.)
There is already an opensource module for connecting magento with openerp, only I dont know till what extend it connects, and if it can connect multiple stores.
The stores at this moment are also completely independent installations of magento, not under the same root. (if this is a really big problem, maybe this could be changed)
Further the installation of openerp should be with spanish module for spain.
And there might be some other modifications to do later on which at the moment I cannot foresee.
If this project can be done positively, 3 other countries are waiting as well for the same job. (we have webshopscompany in Spain, italy, france and germany, we do first a trial in Spain, if everything ok, we will implement the same in italy, france and germany)