This was in a surprisingly very interesting talk on magnestism I was in just last night. The old coins could not be picked up with magnets, but the new ones can, as the inside of it is an alloy.
Also, if you get some tissue, brine, shillings and some 2p coins and soak the tissue in the brine, put them in the order paper,shilling, 2p, paper, you can make a magnet. 4 pairs of coins and tissue created about 0.2v, and using more you can create much more voltage.