it was already rumoured back in March, Nvidia has now officially confirmed that it is licensing SLI technology to motherboard makers for use with AMD CPUs, so that AMD's upcoming, performance-oriented Bulldozer chip can be used with a pair of Green Goblin GPUs.
On its blog, NVidia's Tom Petersen confirmed the rumours that have been around for quite some time and announced that motherboards based on AMD's upcoming 990FX, 990X and 970 chipsets will have SLI support, in case you want to go that way. Tom Petersen mentioned Asus, MSI, Gigabyte and ASRock as first manufacturers that will offer SLI-enabled boards, but other vendors are also expected to join.
Tom Peterson also showed a rather perculiar picture of Asus' Crosshair V Formula motherboard box that shows Nvidia SLI sticker among all other red and one Phenom II sticker, something that honestly just looks weird.
It looks like you won't have to abandon your Nvidia card if you are waiting for some AM3+ fun after all. You can find Tom Peterson's blog here