I recently attended an international scientific conference on autism and yes the role of vaccinations (not just MMR) was openly discussed without anyone going off on one. And the basic opinion was that the jury is still out. Vaccinations may play a role in some situations.
If you want the in and outs of the MMR then the transcripts from the GMC trial and worth a read. Actually you can't read the transcripts because they haven't been released but you can read a report of the trial - on a biased website (Cry Shame) but if you stick to what was actually said then you can get some information. The most interesting thing for me so far was Richard Horton's comments. He was the editor of the Lancet- he is no fan of Wakefield's, but he said the original publication was 'excellent science' which 'still stands'.
What the published results show us is that MMR is safe for the majoirty of children. This comes under the heading of 'no shit sherlock' in my mind. What it doesn't tell you is whether MMR was involved in the 7% of autism cases where the gut is severely ulcerated.
Cochrane (very respected by the medics) have recommended that MMR continues to be used - but also said that the safety trials were wholly inadequate. Usually you see the first bit quoted (continue to use) but then they 'forget' the bit about the safety trials.
So why would singles be safer? Wakefield originally worked on Crohns diseases and found that an 'atypical exposure' to measles virus increased the likelihood of Crohns by a considerable % (can';t remember how much now). This was highly respected work and he was publishing a lot at the time - it was on wild measles virus not vaccine so not political). His belief was that the MMR was an example of an 'atypical exposure' that this was then causing the gut problems at a time when the child was developmentally vulnerable to crashing into autism. He felt that a single jab would be a more 'normal' exposure and therefore safer.
If you look through the literature you'll find lots out there now in highly respected journals on the role of the gut in the pathology of diseases and conditions such as type 1 diabetes, certain types of arthritis, MS, and yes autism (providing you don't talk about vaccines inducing the gut problems you are free to research and publish).
So the question isn't really whether MMR causes autism, but whether the MMR is more likely to trigger a gut reaction which results in a cascade of effects - the end point being autism.
The MMR stuff is now being researched in the States with funding (millions of it) that has come in the main from parents. Not sure how easy it will be to get the results published, but at least the work is taking place funded by an independent body.
It's only likely to have affected 7% of autistic kids. So providing your kid isn't one the the 7% then no problems (and if they are, well no-one will believe you anyway etc etc, much less care).
Of the people I know personally btw who link their child's condition with the MMR, the reactions were medically extreme - some involving stays in HDU or ICU. In one case the paediatrician involved in the child's care did say he thought that MMR was the cause (of the regression).