Passport book vs card

[violetsrblack.livejournal.com]

Hopefully, this hasn't been mentioned already and I missed it.

I was looking at the new FAQ and went to the link for passports. I saw info about the new passport card ($45) which is half the price of a passport book ($100). I thought about getting the book just so that I have it for the future. But for now, it might be easier (read: cheaper) for cruisers to get a card rather than a book. The only difference between the two is that you can not travel by air internationally with it, as you can a passport book. The new card can be used to enter the United States from Canada, Mexico, the Caribbean, and Bermuda at land border crossings or sea ports-of-entry. Both are valid for 10 years.

http://www.travel.state.gov/passport/ppt_card/ppt_card_3926.html

I am going to get a passport card and save the money I would spend on the passport book for another excursion.

Maybe this is something to add to the FAQ?