It's at the UNESCO (or something like that) site. I believe they have various encounters, from being in the water with them ($75) to touching/handling them ($130 or so). Folks say it is great. By the way, Fodor's book on the Bahamas is VERY good. Try their site or a local library (I'm lucky to have a library in my neighborhood :-)
On the encounter, you stand in waist deep water and "pet" the dolphins, as well as get a tour of the facility. The dolphins aslo put on quite a show of leaps and such. These are semi-wild dolphins that can actually leave if they choose, and that makes this one special.