One of the things I could never understand when I owned a Xoom was why it included a barometer. It seemed a rather strange choice of sensors at the time. Dan Morrill at Google posted an explanation... finally it is made clear: it speeds up the time to GPS lock. The Xoom had very good GPS acquisition time so expect the Galaxy Nexus to as well. And thanks to Google for finally explaining the value of a sensor that previously seemed nice to have (you can never have too many sensors), but rather out of place.