Yep, we've been operating using ADS-B in the Gulf of Mexico for about six months now. We're only using some of the ADS-B capabilities at the moment; ADS-B-out but not ADS-B-in (e.g. we are sending a transponder signal out but are not receiving traffic information, weather etc.).
It's been great; IFR routing is now almost direct, largely bypassing the GOM offshore route structure. And spacing is much closer. The other day we followed another IFR aircraft along the same route of flight and within just a few miles (close enough to be on Skywatch). As we were faster than the other aircraft, Houston Center directed us around them via a more direct routing, something they would have never been able to do before.