Lots of articles on this topic including one study on pubmed. It is an important clue for a subset of kids but too many hypothesis and not enough testing.

http://www.autismspeaks.org/science/science-new...

Since his last fever 3 weeks ago.. he now poops in the toilet on his own, went out and engaged play with the little boy across the street, started riding his tricycle, zero severe behavior at schol and one moderate, usually 2 milds that last less than 10 sec tops. more complient and talk alot more

Same here. Our son gets sick very rarely though and even more rare to get fever. Maybe should be sending him to preschool more often!

I thought I was going crazy, during and after a fever Tommy changes by leaps and bounds! He never reverts back

Here is the recorded video on this topic.
http://ariconference.com/?p=802