Very very interesting. I wish I could do things like that too; although when it comes down to it, having far less "special ability" but enjoying a normal, "average-joe" life is much more preferable.
If you're ever tempted to make a pact with the Devil in order to be granted a perfect memory, first read A.R. Luria's The Mind of a Mnemonist. You might also want to read Jorge Luis Borges' short story, "Funes, the Memorius".
It's the opposite of multitasking -- these folks are programmed for one class of functions -- sort of like a CRAY super computer; as I understand it, the speed is derived in part from the fact they are set up as vector processors, and that's all they do.
Trips to the supermarket are always a chore. "There's too much mental stimulus. I have to look at every shape and texture. Every price, and every arrangement of fruit and vegetables. So instead of thinking,'What cheese do I want this week?', I'm just really uncomfortable."
Autistics seem to lack the "filtering" ability our brains use to create order out of multiple stimuli. Even when we go someplace we've never been before, our normal brains automatically filter "irrelevant" information out of our consciousness. We "see" everything, but we don't "note" everything. Our brains make order automatically.
That's why I think autistic people work so hard to create order in their lives.