Apple UK has sent out an email invitation to select media outlets announcing a press event to be held at the Apple Store, Regent Street in London on September 18 at 10:00 a.m. The invitation reads simply, “Mum is no longer the word.”, and includes directions to the store. The event could likely be used to introduce the European version of the iPhone; however, no confirmation of such an announcement has yet been given by Apple, or by the…