Facebook is the de facto social networking site today, but you shouldn't forget about the rest of the sites, since their services are used by quite a lot of people as well. They are somewhat different from Facebook, so there are a few guidelines to consider when using them.
Images play a pivotal role when selling a real-estate - buyers get a glimpse of their prospective new homes and decide whether they are going to buy it or not. Therefore, there's even more responsibility on the shoulders of real-estate agents if they publish their work on a social networking site that deals mainly with images.