Photo ID in the US
After October 28, 2002, the FAA requires pilots to carry photo ID.
Here's an extract from the rule: The FAA revises 14 CFR § 61.3(a) to require each person to carry a photo identification when exercising the privileges of a pilot certificate. The photo identification in most instances likely will be a driver's license issued by a State, the District of Columbia, or a territory or possession of the United States. It may also be a government identification card issued by the Federal government or a State, the District of Columbia, or a territory or possession of the United States, a military identification card, or a passport.
Note the emphasis on US Government issued ID. Does any one yet know whether a foreign passport (or other photo ID) will be acceptable for visitors in the US who wish to fly?