The University of Washington School of Medicine in Seattle, USA released autism research results in August 2006 in the Neurology medical journal. The medical journal itself is pretty thick with medical jargon however, so I recommend reading the Forbes summary referenced at the end of this article instead, since it's written in plain English.
To save you time though, here is the crux of the research results.
* young children with autism appear to have enlarged brains - about 10% larger than 'regular' kids
* an enlarged brain does not necessarily correspond with faster brain growth
* indications are that the larger brains are due to an inflammatory condition, rather than faster brain growth
* indications are that the brains of autistic kids have more liquid - cause unknown
* these results are contrary to popular theories of faster brain growth resulting in 'disorganized circuitry'
Bear in mind that this is my layman's interpretation of the results and of the Forbes article, but I think that it pretty well sums up the results of the research in a way that is useful to parents and teachers dealing with autistic kids.
It appears that ongoing research is doing great things to dismantle current thinking about the disability of autism, but isn't yet bringing us any closer to prevention, cures or treatment.