"The Coral Reef Aquarium" by Tony Vargas seems to be a pretty popular and recent book about the hobby. It has a lot of up to date information about new "dream tank" setups and what hobbyists do to maintain these setups. It's something I am interested in buying.
I still feel like the three volume set up Julian Sprung and Dr. Charles Delbeek's "The Reef Aquarium." are still relevant to this day. Even though the equipment has changed over time, the requirements to keep corals alive pretty much have not changed over time. They still have pertinent information to the hobby.
A book solely on corals that is still relevant is Eric Borneman's "Aquarium corals" Like I said, even though the equipment has changed, the methods to keep a tank healthy have changed very, very little over the last ten years