Interverbal's blog has a great discussion about the significance of the recent California autism numbers.
He's following up on a post on Ginger's blog that tried to demonstrate a perceived drop in the increase of autism cases in the state and also attempted to correlate that the drop (given the corresponding time lag) with the reduction of thimerosal in the vaccines given to young children.
On Interverbal's blog you'll get dry data and conservative but accurate analysis. He skips the posturing and melodrama all too common in discussions of autism. So check it out.
Bottom line: the jury's still out about the roots of autism.