Looks like we'll have to wait even longer for SLI on the 990FX chipset as it won't work with the current Nvidia driver.....http://www.eteknix.com/news/9-series-am3-motherboards-still-cannot-utilise-sli-1263/
I've just been hunting about the interwez and it seems like it's only affecting some boards, looks like the 275 drivers will have it fixed.