No, hell isn't frozen yet, and no, this isn't a delayed April Fool's prank, Nvidia has actually announced that it has licensed its multi-GPU technology (SLI) to companies building motherboards based on AMD's AM3+-supporting 990FX, 990X and 970 chipsets.
As a result of this change of heart (read business decision) Asus, Gigabyte, ASRock, MSI and others will build and sell AM3+ boards that support both CrossFire and SLI. Up until now Nvidia blocked SLI on AMD-based boards but since it's no longer making chipsets, it caved in, as it did with SLI on Intel motherboards.
So, there you have it, SLI is ready for Bulldozer.