There are SO many things that we have increased/discovered in the past 30 years (like ultrasounds) and a much higher diagnosis rate of ASD (well, first the acceptances of it, and even now in next years DSM-V there will be a huge change - no PDD-NOS/Aspergers/Autism - it is all 1 spectrum), so it is very hard to distinguish between causation and correlation. And that ASD in general if they are high functioning (and female as Ryn pointed out) are hard to diagnose.. gosh, it is so hard you wonder if we will ever understand it.

Anyway, some interesting blogs I have found are:
Adventures in Autism: Its Not Just The Mercury: Aluminum Hydroxide In Vaccines
Aluminum Toxicity: A misdiagnosed epidemic (Part 1) By Ingri Cassel

Oh, another thing I heard on an interview with the guy from Catalyst today was they are currently developing inhaled vaccinations (taking the liquid vaccine and making it be able to be delivered by airborne particles like a asthma puffer rather than an injection). Apparently it is one of the changed we are going to see soon. Wondering if that will change the vaccination make-up.