You will not be able to use SLI with that motherboard. You need currently a Nvidia 980a motherboard or Nvidia 750a motherboard for SLI.
It looks like the new AM3+ motherboards will have SLI support on the FX boards based on current news. If you are wanting to run SLI now, I would look at a Sandy Bridge setup (though I've heard there may be another issue with them
) or wait for the AM3+ boards to be released.