I came across the US government's web page regarding the soon to be implemented change in travel documents.

Here's the jist:
After December 31, 2005, you will need a passport to reenter the US from Jamaica and other countries which currently require only a birth certificate and driver's license.

Here's the web pages:
http://travel.state.gov/travel/cbpmc/cbpmc_2223.html
http://travel.state.gov/travel/cbpmc/cbpmc_2224.html

Here's the main text:
Travelers to and from the Caribbean, Bermuda, Panama, Mexico and Canada will be required to have a passport or other secure, accepted document to enter or re-enter the United States.  This is a change from prior travel requirements and will affect all United States citizens entering the United States from countries within the Western Hemisphere who do not currently possess valid passports.   This new requirement will also affect certain foreign nationals who currently are not required to present a passport to travel to the United States.  Most Canadian citizens, citizens of the British Overseas Territory of Bermuda, and to a lesser degree, Mexican citizens will be affected by the implementation of this requirement. 

December 31, 2005 – Passport or other accepted document required for all travel (air/sea) to or from the Caribbean, Bermuda, Central and South America.