Latest super-tall Miami proposal is an office tower One Bayfront Plaza. Despite a slowdown in residential demand and construction, office demand and construction in Miami has shown to signs of slow down. Located in the central business district across from Bayfront Park, the proposal 2.1M square feet of commercial space, a two-storey mall at the lobby with 120,000 square feet of retail space, and a 650 room hotel (located in a second, smaller tower), and 3,000 parking spaces.
http://www.fecr.com/bayfrontPark/index.htm
It will be interesting to see how it moves foward. Being a commercial project, I don't think it has a bad chance of happening.