In theory its possible. The X58 shows that its most likely a licencing issue rather than hardware. But if they allowed it for the P45 chipset it would take away from nvidia board sales so i doubt it will happen. It would be more than drivers as well, it would have to be a bios update im pretty sure.
EDIT: Nos' got in before me - he might be right, but i havent heard there was any extra hardware for SLI on the x58...