Check out the thread down a little ... OK here is a link:
http://www.findmall.com/read.php?26,1792284
One experience I had about a year ago on a Florida visit was that I could hunt openly on the beaches in front of the hotels and resorts, then I hit a one block section that was the Palm Beach Shores City beach park. I was in the water and had not seen any signs as I entered this block. As I headed from the water to some wet sand a guy on a 4 wheeler sped over and told me no detecting. I asked if it was posted, he pointed to where the sign was way up by the dunes. I turned the detector off and asked where the other boundary was. He pointed. I thanked him for pointing it out, we chatted about what I find (mostly trash, some change, get some exercise, etc) I asked him if he wanted the bottle caps I had dug on the restricted area, he declined. We shook hands and I headed to the edge of the private area and resumed hunting. On my return back towards the hotel, I walked up and read the sign and it did indeed say no detecting (among many other things that were not allowed). Turned the detector off for that block then resumed hunting on the other side.
Good luck when you take your trip!
Cheers,
tvr