Crossfire vs SLI ... Hardware?

Ok, this is going to be a stupid question, and for that I apologize, but regarding motherboards, they are either SLI or Crossfire, correct? (Assuming they are one or the other) So I cannot buy a SLI motherboard and use it for Crossfire setup and the same the other way around?

as far as I know this isn't feasible. There was a hack to get SLI running on CF and ULi dual GPU boards, but I think it depended on using old drivers that had been leaked by ULi engineers. I think somebody did CF on an SLI board too, but again I it was a hack job (though I can't actually remember for sure whether it happened at all).

Its possible becuase the hardware is designed to run multiple GPUs but it would require alot of work to create modified chipset and motherboard drivers to make it work.