Now everyone knows that Intel X58 mainboard is SLI capable. But you are not getting SLI enable for free. Sources told us if company want to enable SLI on their X58, they need to send examples to NVIDIA for certification, and after that NVIDIA will charge mainboard company 5 USD for each mobo they have shipped in the future. Currently only four companies and ten have X58 SLI licensing:

ASUS: Rampage II Extreme, P6T Deluxe
MSI: Eclipse SLI, X58 Platinum SLI
GBT: GA‐EX58‐UD5P, GA‐EX58‐Extreme
DFI: LP UT X58‐T3eH8, LP DK X58‐T3eH6, LP JR X58‐T3H

Of course, we can expect more X58 with SLI from ECS, Foxconn and EVGA (yes, EVGA will going to make Intel Chipset mobo) .