For information regarding the Chinese drywall issue please go to www.drywallresponse.gov

In summary:
The CPSC (consumer product safety commission) has released several documents (click on title for .pdf doc)
Interim Guidance – Identification of Homes with Corrosion from Problem Drywall
Interim Remediation Guidance for Homes with Corrosion from Problem Drywall

List of states where problems have been reported  http://www.cpsc.gov/info/drywall/drywalldist.pdf

The vast majority of problems were reported in Florida with several other southern states experiencing problems also.  Here is a picture showing the states with the largest percentage of reported problems.