The next socket from Intel is supposed to support quad channel. AMD is staying with dual as far as we know. You can run the quad kit of memory, but in dual channel mode.
Sure, any AM3 motherboard with four (4) available DIMM slot can run 4 sticks of RAM. No CPU on the market today, AMD or Intel, actually runs quad channel.
I would point out: you will get Better OC'ing performance on your RAM if you only have 2 sticks. You'll get higher frequencies at lower voltages every time. SOOOOO, I would definitely go for 2 x 4Gb sticks over any 4 x 2Gb setup. This is true for any AMD CPU any Intel CPU........
Two 2 sticks of any brand, any speed, and any timings will Always Easier to run faster than 4 stick of same brand, timings, and speed... (at lower voltages too...)