I am a healthcare scientist (infectious diseases) and I have two children who are at the mild end of the autistic spectrum (high functioning/Asperger's). I was taking my MSc when the whole furore about the MMR started so had to form an opinion about Dr. Wakefield's research, then looked into it again when I had my children, and have been keeping an eye on what's going on with it via Medline (abstracts from peer reviewed, published papers can be viewed for free on-line through Pubmed, amongst others).
As far as I can see there is no research proving there's a direct causal link between the MMR and autism, and a lot of research against it. There are a few studies with a question mark against mercury which is more likely to be environmental than through vaccination (For example see this -
http://www.ncbi.nlm.nih.gov/pubmed/19106436 ) and which may possibly affect some children with a (possibly genetic) predisposition towards autism, although there needs to be further research into the mechanisms
There seem to be a number of different causes of autism, so in any case what causes it in one child won't cause it in another, but there seems to be a genetic link in most cases. As another poster said, they are also diagnosing a lot more of the milder cases now, and I would actually question the 1 in 98 figure - in my kids school it's probably 1 in 60 or higher (anecdotally) since I personally know three other children on the spectrum, but at the mild end they largely fit in, have (sometimes odd) friendships and do well.
I do think though that this is a subject which is very complex, and people have to make their minds up based on their experiences and reading. I agree with JSB in that it's worth doing some research, and I'm also a BIG fan of vaccines (single if it makes you happy
).