We just purchased a 2005 Passion Cabrio with less than 10,000 miles on it. It is now tagged and titles in Austin, TX. Our other vehicles include a 2007 GMC Sierra pick up and a 2007 Toyota Camry Hybrid. Even with two other newer vehicles the wife and I are often playing a game of who gets to drive the Smart today.
Once the new ones start to grab hold in the States I can easily see us getting another Smart. We're still on the waiting list, but will have to wait and see how it plays out over the year or so.
We lived in Europe for over 6 years and saw these everywhere over there. We've been keeping out eyes peeled for one in the States and finally found it this last week and couldn't be happier with our purchase.