This MAP plots where Twitter is used by iPhone, BlackBerry or Android [MAP]

Check out this map, which plots colored points on a map of Baltimore indicating where in the city people are using an iPhone, Blackberry, Android phone or some other mobile device to post on Twitter.
A large concentration of iPhone users, according to this visualization, post to Twitter in downtown Baltimore, north of the Inner Harbor but south of Mount Vernon, with a decent amount of activity around where Camden Yards and M&T Bank Stadium are located.