The LA Times recently published a four-part investigation of autism. It’s pretty good, it has more information on it than I’ve been able to find in my own research elsewhere.
I’m not a scientist, and I’m operating solely on my own experience and what I’ve read of others, but it seems to me that autism is a broad diagnosis of a malfunction in certain parts of the brain, parts that are different for each sufferer. Sometimes early intervention allows the child’s brain to rewire itself to bypass the malfunctioning parts; in other cases, areas critical for recovery are too damaged to compensate. For some, the same malfunction may also result in developing skills or abilities that people don’t normally have as well: perfect pitch, a dramatically better memory for places and physical layouts, superior mathematical skill, or something similar.
I’m not sure it would be possible, especially at this point in medical science, but classifying autistics by the affected areas might be useful. Then again, once science advances far enough to do that, we may well find that most people suffer from such problems, and autistics are only different by the kinds of areas affected (often social and language) or the number of them.
Just my two cents’ worth.