The Android mobile platform served over of the US smartphone market in February, according to a monthly report from Millenial Media which found Google’s OS captured 51% of all mobile ad impressions.

Apple’s iOS was the next most popular, with 27% of impressions, then RIM with 17%.

The report also revealed the increasing popularity of smartphones, with those devices representing 62% of mobile ads served, 25% served through ‘feature phones’, and 14% through connected devices.

However, it is the connected device category that has seen the fastest recent growth, with impressions through gadgets like tablet PCs and iPods increasing by 56% on the same time last year.

Of the top 30 most popular mobile devices, Android devices accounted for 19, up from 16 the previous month. Download the full report here: http://www.millennialmedia.com/research/