I was in Copenhagen last month and can confirm that I saw the additional fee for foreign credit cards mentioned on many restaurant menus. It didn't seem to be an issue everywhere - I paid with a U.S. cc for a purchase at the Illum department store without being charged the fee - but was very noticeable on menus. I just withdrew additional cash from an ATM and avoided credit card use - I was only there a couple of days before continuing on to Sweden, so it wasn't that big an issue for me.