Microsoft have, to be blunt, squandered their position as market leaders in the smart phone market. Having worked their way to the top of the charts (for at least business users), 2009 saw their popularity drop to just third place.
To my mind, this was largely due to neglect. To all but the trained eye, many parts of the operating system remained largely unchanged between 2001 and 2009. The main 'Today' screen being a good example of this.