Google’s Android OS had a 9% share of the US smartphone market in February, up from 3.8% last November. That’s based on strong sales of handsets like Motorola’s Droid. However, it’s still only the fourth most popular smartphone OS in the US, behind BlackBerry (42.1% market share in February), iPhone (25.4%) and Windows Mobile (15.1%). This is based on figures from comScore, which has also recorded an increase in the percentage of US mobile users listening to music on their phones. In November, it stood at 11.8%, but by February it had risen to 13.1%. That’s still behind games (21.9%) and social networking (18%) though.