INTERBOOK, a telephone gift service that will do for books what Interflora does for flowers, was launched last week. All books are charged at their published price, and the service includes courier delivery to anywhere in mainland Britain, gift wrapping, a greetings card, a printed message on a bookplate, and insurance. It costs pounds 4.99 per address for next-day delivery (providing the order is taken before 3pm) and pounds 4.25 if three days' notice is given. Credit card is the only form of payment accepted. The Interbook Gift Line is 081-200 1515.