From MSNBC.com [1]:
The largest U.S. study of childhood autism to date has found that about 1 in 150 have the disorder — a higher prevalence than previous national estimates.
The autism rate was about 6.6 per 1,000 in the new study based on data from 2002. It was released Thursday by the U.S. Centers for Disease Control and Prevention. Last year, the agency had estimated the rate was about 5.5 in 1,000.
The research involved an intense review of medical and school records for children in all or part of 14 states and gives the clearest picture yet of how common autism is in some parts of the country, CDC officials said.
1 in 94 children in New Jersey have autism. That is very, very sad. It is shocking how fast the identified inceident rate has increased [2] in the last couple decades. e.g. California has seen an increase of 273% [3] in the last decade.

Links:
[1] http://www.msnbc.msn.com/id/17047721/
[2] http://en.wikipedia.org/wiki/Image:Autismnocgraph.png
[3] http://www.pediatricservices.com/flash.htm