Yes, copper keeps slugs away. They will not cross it. I was actually talking to my mate about this up the pub last night as he uses copper on his allotment to keep slugs off.
Just something I found when googled......
"Copper strips. When a slug touches copper, it is charged with current, an unpleasant experience that makes it reverse course. Place a band of copper (preferably 3 inches wide) around beds or individual plants. Or form copper wire into a tight, conical spiral around each plant, with the small end at the bottom, and push the wire into the soil. Make sure slugs are not trapped inside barriers."