I don't think that is true. I looked at doing a Celebrity cruise out of NJ this October that sails from NJ to San Juan and the only foreign port is St. Thomas which is still considered North America.
I have also looked at a NCL repositioning cruise from Tampa to NY and the only ports are in the Caribbean and Mexico which are considered North America.
Probably the person who wrote that on Wikipedia either didn't understand that Puerto Rico is the US or that the Caribbean and Mexico are also North America!!!
St. Thomas is in the US Virgin Islands, so it's not a foreign port. I was on a repositioning cruise from San Juan to Norfolk, VA, and it stopped in St. Maarten, Tortola, and Bermuda - as well as St. Thomas. (Before that it went from Tampa to San Juan.)
Wikipedia may be wrong about North America, but there is still the "distant" foreign port requirement for ships traveling between two different US ports.
Cruise ships that regularly visit Hawaii don't tender in all the ports. I have a Honolulu to Vancouver cruise booked for 2012 that goes to 5 ports on 4 islands. It docks in Honolulu (Oahu), Nawiliwili (Kauai), and Hilo (Hawaii), and tenders in Lahaina (Maui) and Kailua-Kona (Hawaii)