The BBC News reports that businesses are suffering from their slacker employees taking Friday afternoon off.
An alternative explanation is possible, though - that some of these businesses are so overworking their employees during the week that by Friday afternoon they are completely spent. Good management isn't about ensuring your staff are in the office for the maximum time possible - it's ensuring your staff do the most useful work possible. If they're burnt out by Wednesday, they could well be spending Monday and Tuesday fixing the errors that they and others made the previous Thursday and Friday.
Just in case anyone is speculating, the person responsible for giving me too much work to do at the moment is myself.