New requirements take effect January 31 on travel to Canada.

http://www.dhs.gov/xnews/releases/pr_1196711811270.shtm

Beginning January 31, 2008, U.S. Citizens traveling by land or sea will need to present the following to enter or depart the United States:

Ages 19 and older: a government-issued photo ID, such as a driver’s license, along with proof of citizenship, such as a birth certificate or naturalization certificate

• Children ages 18 and younger: proof of citizenship, such as a birth certificate.

Also, new US Passport Card available in Spring 2008.

The Department of State is issuing this passport card in response to the needs of border resident communities for a less expensive and more portable alternative to the traditional passport book. The card will have the same validity period as a passport book: 10 years for an adult, five for children 15 and younger. For adults who already have a passport book, they may apply for the card as a passport renewal and pay only $20. First-time applicants will pay $45 for adult cards and $35 for children.

http://travel.state.gov/pdf/WHTI_Passport_Sheet.pdf

This article talks about the single and two document options and the new passport card available in the Spring (can be ordered starting in February).

http://www.cbp.gov/xp/cgov/travel/vacation/ready_set_go/land_travel/chnge_in_proced.xml