You could try to let them get to know each olther but keep both of them on leashes wso they can be pulled apart if anything happens.
Both dogs need to be taught that their respective owners are the pack leaders and nither of them is. this will take some training for the humans to start behaving as pack leaders and stop spoiling the dogs.
http://www.dogchannel.com/experts/ce...aspx?WT.srch=1