The OpenSen blog reviews some recent developments for children on the autistic spectrum including a variety of humanoid robotics, kinectwiki, Cospatial, Reactickles magic and a virtual environment- Echoes:
Echoes is a technology enhanced learning experience, where young people with ASC can explore in a virtual learning environment by interacting with Andy an intelligent virtual character. Andy encourages exploration and provides opportunities for social communication in a virtual magical garden and during some hands on time with the software I was able to sort and move flower pots, collect items, throw a bouncing ball, shake rain clouds to create raindrops that allowed me to grow flowers and burst bubbles, all with Andy’s encouragement. Andy could helpfully look at items to prompt further interaction and sign to me using Makaton, even when we tried to be unhelpful by playfully soaking Andy with a rain cloud, we weren’t scolded or corrected, instead Andy continued to provide prompts to other areas of interest and opportunities that would create a more positive result from our interaction
One Change a Day 
A tricky area – perhaps even more than as is seen with ‘normal’ children, there is a risk of retreat into the virtual world without any real improvement in reaction to the real one?
I don’t know enough about it personally, but it looks like an exciting way to assist in learning.SmartLabs have done some interesting work with virtual environments too and some very positive results