The fan itself will be a full two slots and have four heatpipes. These will be cooled by a 100mm fan.
The three models will be the R4890 Cyclone (850Mhz/3900Mhz), the R4890 Cyclone OS (880Mhz/3900Mhz) and the R4890 SOC (1Ghz/4000MHz). Availability should be in the next few weeks. There is no word on pricing as of this writing.

Picture courtesy of TechConect Magazine.