If you have more than one Mac on a network, you can share each Mac’s photo libraries and make them accessible to the other Macs on the network, as well as to a second-generation Apple TV.
Network photo sharing leads to all kinds of possibilities. Keep your “master” photo library on one Mac, and then access it from other Macs when you need to—no need to copy the library from one Mac to another and worry about which library is the most current.
Don’t like centralization? Embrace anarchy: let everyone in the family have his or her own photo library, and then use sharing to make the libraries available to others.
Have an AirPort-equipped laptop Mac or an Apple TV 2 connected to your HDTV? Sit on the sofa (or at poolside) ...