It may seem obvious that the maps stored on GPS devices is not always correct. Not only is the data collection itself prone to error, but they are a static snapshot. Maps change overtime, new roads are built, natural disasters take out roads, and civil projects can lead many roads and towns to be at the bottom of a lake.
There was an episode of the office where one of the characters drives his car into a lake, because his GPS told him so, a clip can be found here.
The linked article doesn’t take into account error with the GPS itself. GPS error is very common, especially in areas where the signal can reflect or be distorted. A popular example of this can happen in an Urban Canyon. I have seen a GPS estimate its location as being on a major highway, when a vehicle was traveling on a frontage road, as well as some very peculiar effects biking through New York City.
While not as readable as a USA Today article, Wikipedia has a very good article up on errors in GPS reception.
Caution: GPS devices aren’t always right. (via USA Today)