I just read the first story in Gardner Dozois' 2004 collection - Pat Murphy's "Inappropriate Behaviour" - and it is about a girl with autism. Two of the stories in the Hartwell/Cramer collection also featured brilliant academics with autism - Terry Bisson's "Scout's Honour" and Brenda Cooper's "Savant Songs".
There are a number of other sf stories, some well-known, others less so, featuring autism. Elizabeth Moon's The Speed of Dark of course won the Nebula Award two years ago, and deals specifically with a "cure". Most of the others feature an autistic child as the centre of some almost (or even explicitly) magical events: Mary Doria Russell's Children of God, Zoran Živković's short story "The Whisper", Philip K. Dick's Martian Time-Slip, William Gibson's All Tomorrow's Parties. I also rather liked Brenda Clough's "Tiptoe, On a Fence-Post" where the autistic child was marginal to the story but gave the author an excuse for some sensitive character-building.
Other sf stories that I understand feature autism which I haven't read: Greg Egan, Distress; Dean Ing, "Portions of this Program…"; Diane Duane, A Wizard Alone; James B. Johnson, Daystar and Shadow; Megan Lindholm, The Reindeer People and Wolf's Brother; Jane Lindskold, "Brother To Dragons, Companion To Owls"; Charles Sheffield, Putting Up Roots; Elizabeth Hand, "Chip Crockett's Christmas Carol" and Winterlong; Jeffery D. Kooistra, Dykstra's War; Ian Watson, "The Boy Who Lost an Hour, the Girl Who Lost Her Life"; Kathleen Anne Goonan, Light Music; Kathryn Lasky, Home Free; Celia Rees, The Truth Out There; Mira Rothenberg, Children with Emerald Eyes; Eric Brown, New York Dreams; apparently the new Thomas Covenant series; Kathleen Burns, Something's At My Elbow; Lucius Shepard, "The Emperor"; Frederik Pohl and C.M. Kornbluth, "The Meeting"; Paul Park, "The Breakthrough"; Robert Silverberg, Thorns; Alan E. Nourse, The Universe Between.
Anyone want to particularly recommend (or dis-recommend) any of those, or add to the list? I don't know for sure if autism is a subject which crops up more often in sf than in "mainstream" literature, but it seems rather likely; I can't think of any non-genre novel dealing with it apart from Mark Haddon's The Curious Incident of the Dog in the Night-Time, but then I don't read an awful lot of non-genre fiction.
For the sf writer, different ways of perceiving and sensing the world are of profound interest, and the enigma of the autistic experience is perhaps an attractive topic. (Of course, this tends to mean that the autistic characters are rather bunched towards the high-functioning end of the spectrum.) For a writer with personal experience of autism, projecting this crucial experience into a fantasy or far-future milieu may also be an important part of the coping mechanism. (I find it interesting that writer Nick Hornby, who has an autistic son, has never used autism in his fiction, which is set in the gritty contemporary world.)