any gps improvement on smartphones with barometer? I know that smartphones gps have problems with their accuracy, especially with altitude. But I heard that the Galaxy Nexus has a barometer that theoretically is used to improve the accuracy of the gps.

Anyone has used it to track any route? It can compare (in accuracy) to a mid-range bicycle gps device?
Barometric altitude is far more accurate than GPS over several hours IF you have it corrected for the air pressure. Air pressure does not vary quickly. 
So if you calibrate a barometer to a known altitude (using a marker, sign, map, or very good GPS fix) it is much better than GPS for measuring an altitude profile