Pictures of an AM3 reference board with AMD's 890FX chipset have been published on a Dutch website.
The 890FX motherboard offers four PCI-Express 2.0 x16 slots and slots for DDR3 RAM modules. Furthermore there are one PCI-E x4 and one PCI slot. This 890FX board is supposed to be AM3 exclusive and apparently won't support AM2(+).
The 890FX Northbrdige has an active cooler and isn't located below the CPU socket but diagonally above it. The new SB850 Southbridge is covered with a small black passive heatsink as you can see on the pictures from Bouwennpc.