From the sounds of this article from the Windsor Star, US Border Services have a good handle on the passport issue for returning to the US from Canada and there are no extra delays at the border entering the United States.
"Both passenger and commercial traffic were flowing normally, with only brief warnings issued by U.S. border guards for those without the proper documents.
A small paper information leaflet with a banner of "non-compliant" was given to anyone who failed to produce a passport or other satisfactory documents under Washington's Western Hemisphere Travel Initiative rules, which also allow for use of enhanced drivers' licences or NEXUS cards to enter the U.S. at land borders.
"The new rule has not affected our traffic at all, and we don't anticipate it will," said Chief Ron Smith, spokesman for U.S. Customs and Border Patrol in Detroit. "We know we are going to have people crossing without documents. It's not our goal to stop traffic, but instead, go through an informed compliance period so people know what they need to do."
Hope this article helps anyone contemplating a vacation in Canada this summer who does not yet have a passport, enhanced drivers license, or NEXUS Card.