I don't particularly like thinking of autism as disordered versus non-disordered. I don't like thinking in terms of pathology because in evolutionary terms, either you pass your genes on or you don't, and in the meantime, either your phenotype helps you to pass those on or it doesn't. There's no "disorder" in nature. That's a human label.
I see autism (Autistic Disorder, Aspergers, PDD-NOS) as genetically related within families since they often occur within the same families. Between families, there's probably some variation although still maybe some larger genetic markers in common. I think autism, "disorder" aside, makes up a solid portion of the population, leading up into a Broader Autistic Phenotype which I still consider autism although which may not win a diagnosis by a professional. Still, it's the same underlying issues. To me, I find little sense in trying to separate out the different labels used today from one another; I don't bother to take part in discussions these days as to whether Aspergers should be considered "autism" and "What are the differences between HFA and AS", etc. To me, these variations are no longer very relevant and not particularly integral in my view to understanding the whole of autism.
Instead, I prefer to look at the similarities and differences from person to person, rather than label to label. I think things are clearer that way. I like thinking of "autism" from brain to brain, body to body. Generalizing things too much I think runs the danger of ignoring the fact that evolution (unwittingly) designs each creature anew, albeit based on the genes it was given. But each creature is still a new attempt to beat the next one to reproduce, whether they're of the same species or not. And either they're successful or they're not.
I look at behavior and mental processes and genes the same way!
Like the article Max referenced (shadow syndromes), the number of "disordered" or "pathological" diagnoses in the DVM has jumped to over 400 now (from 80), which makes the terminology nearly passe at this point! What is "disordered" when nearly every behavior IS disordered?
I see autism (Autistic Disorder, Aspergers, PDD-NOS) as genetically related within families since they often occur within the same families. Between families, there's probably some variation although still maybe some larger genetic markers in common. I think autism, "disorder" aside, makes up a solid portion of the population, leading up into a Broader Autistic Phenotype which I still consider autism although which may not win a diagnosis by a professional.
I agree totally with the above, that if you could capture the "autistic" (primarily thinking vs. feeling; solipsistic vs. emphathetic, etc.) tendencies in the greater population, the one not yet diagnosed, you would find that it DOES "make up a solid portion of the population". Maybe someday it will be seen as comprising a near majority even (40 or more percent).
To me, the final, and only truly important distinction is one's spiritual status, which varies from soul to soul, and which will never be quantified by science. All other distinctions- gender, social status, the intelligence quotient, etc. - are meaningless and should never be subject to categorization like "good, better, best" because they merely reflect the shell, the "costume", the role, the soul has elected to take on to learn certain worldly lessons, to grow spiritually. For example, most Perfect Masters work in obscurity, but if you are ever lucky enough to come into their orbit you will find they appear often like madmen, oblivious to their clothes, hair, appearance. They mostly live in the East 'cause they would be institutionalized (or people would try anyway) in the West. 
To get back to genes, since AS was originally a N. European gene, it will probably just manifest itself in a big way where racial/cultural (Jews AND Christians; Buddhist AND Christians, etc.) inter-marriage is possible/condoned (and also where there are many more personal freedoms) and so will be most concentrated in developed countries probably and slower to manifest in Africa, China, the Middle East.