Based on my limited understanding, the trend now is to see Asperger's Syndrome as one point on a spectrum of characteristics (the more functional end) of autism. There is a greater ability to understand and manipulate abstract data than human interactions in such kids. My guess is there is a touch of Asperger's in a lot of us.
It also may be genetic. The schools in Silicon Valley have a much higher concentration of children with Asperger's, possibly the result of the larger number of parents in the computer industry marrying and having kids. As a result, the (very) well-funded schools in Silicon Valley have developed a lot of educational techniques for these kids. Here is an interesting article from
Wired magazine on the subject:
http://www.wired.com/wired/archive/9.12/aspergers.html
One theory I've heard is that autism and Asperger's (which apparently are more common in males) are just the male emotional characteristics writ large. Guys are
generally less adept than women at forming social relationships (especially as we age), worse at reading emotions, and more comfortable talking about abstract data (sports scores, trivia, jokes, movie scenes) in conversation, whereas female conversation tends to be more based on feeling, relationship, and emotion as topics. (That's the stereotype anyway, one with which I don't fully agree.) One causative theory of autism is an imbalance of male hormones in the prenatal environment, and the presence of very "ripped" musculature at birth (like 6-pack abs) is a strong indicator of autism.
There is a recent novel whose protagonist is a boy with Asperger's Syndrome, I think the title was "The Curious Incident of the Dog That Barked at Midnight". I haven't read it but my wife recommended it.