In my mind, it is impossible to classify Einstein as Autisitic. I went to prep school where, for two years there was an autistic-savant also attending. This person pretty much matches all the descriptions of autistic-avants I have read since, and does not match anything I've read about Einstein.
Asperger's doesn't fit Einstein, either, for two reasons: 1.) As SelfAdjoint pointed out, Einstein was too socially at ease, and: 2.) Asperger's people tend to be academically above average, not below, as children. They strike the people around them as brighter than average.
Regarding the story about his brain, I specifically read that the people who examined it were baffled because they could find nothing whatever unusual about it. Their verdict was that it was the normal brain of a 75 year old man. They had been hoping to find something different to account for his intelligence, but couldn't.
It is quite possible that Einstein started out with some neurologically based learning disabilities, based on the reports of his difficulties with learning in some areas as a child. Learning disabilities do not automatically, or even usually, mean a diagnosis of autism or Asperger's (especially not Asperger's).
Each child with organic learning disabilities has his or her own particular set of problems. They are all different from each other, and all different from autistic kids.
The suggestion that Einstein was autistic, which has been seriously bandied about, never holds up when you look at what he was like and how autism presents.