I can thank Jean Kazez for recommending this book. I'm not very far into it, and I'm already finding points to disagree with. But it's a very clear, accessible, and (judging by the table of contents) comprehensive text on current philosophical ethics. I'm sure I'm going to enjoy the whole book.
It was published only last year, so we'd all be struggling to think of a more up-to-date introductory text on this subject. At this early stage I'd rank it above James Rachels' equivalent book, even though the latter is also very good.