A Video Glossary has just been released jointly by two groups, Autism Speaks and First Signs. The video contains a number of clips the early stages of children that have been diagnosed autistic. It is very informative.
Also, the American Academy of Pediatrics is apparently about to release a report, suggesting that all children should be screened for autism at both 18 months and 24 months. A link to an article about this can be found here.