Telecoms-focussed consultancy iGR has been asking US-based mobile developers what they're working on and what their plans are.
53% of the developers were building applications for the Apple iPhone OS, a change from iGR’s 2009 developer study in which Windows Mobile was the most popular operating system. In 2010, the most popular platforms after the iPhone were RIM BlackBerry, Android and Microsoft Windows Mobile 6.5.
Respondents currently developed for an average of 2.4 separate platforms, with an increase to 3.4 expected over the next 12 months. More than half of those not currently developing for the iPhone platform were planning to do so in the next 12 months.