According to the Q4 2011 U.S. data released by Nielsen, Microsoft has caught 1.3% of the "current smartphone consumer" market, whereas they've attracted 1.4% of recent smartphone acquires (within the 3 months). Windows Mobile is set at 4.6% with Blackberry holding 14.9%. Windows Mobile is still being pumped out (more being sold than Windows Phone) but Blackberry is struggling to attract smartphone upgrades.
iOS saw an increase with the recent iPhone 4S launch, which has been relatively successful, while Android storms ahead taking almost half the market (46.4%) and attracting 51.7% of the recent smartphone acquires. For 2012, Microsoft (as well as the platform OEMs) have a task to win the minds of consumers and catch the majority of new adopters. With the beginning of the U.S. push, and marketing still ongoing across Europe and beyond, we should hopefully see some results in the Q1 2012 report.