This topic is well outside my sphere of "expertise", but within my concerns as a parent and as a friend of other parents.
Robert F. Kennedy Jr. suggests here that if researchers are interested in studying the link between Thimerosal and autism, it would be well within the "Duh!" range to compare American populations of vaccinated kids with their non-vaccinated peers in Amish communities et al.
Like I said, I'm shamefully uninformed on the controversy, beyond what little I've heard in the mainstream press here and in the U.K. (it was a hot topic while we lived there, with much pressure coming from British parents to ban the MMR combined-vaccine).
If anyone has any good resources for getting up to speed on the topic, I'd be grateful if you'd share. Thanks.