The outlook has been grim for RIM’s BlackBerry platform for some time, and new figures out today from comScore add to the gloom.

The data company’s report, looking at mobile market share in the US in October 2011, shows BlackBerry dropping 4.5 percentage points in terms of share of smartphone subscribers since July, dropping to 17.2% of the market. Meanwhile, Google’s Android has gained 4.4 percentage points, extending its lead with 46.3%. Apple saw a modest gain rising 1 percentage point to 28.1%.

Meanwhile, Microsoft and Symbian’s market shares by platform both saw modest 0.3 percentage point declines in the three months up to October.

Screen Shot 2011 12 02 at 17.44.51 Android gains ground from BlackBerry in latest US mobile comScore figures

There was little change in terms of manufacturer market share though. Samsung held steady at the top, with 25.5% of the market. LG, Motorola saw modest declines of less than 1%. RIM was down 1% and Apple saw a 1% gain, perhaps helped by interest in the iPhone 4S, released in mid-October.

Screen Shot 2011 12 02 at 17.44.28 Android gains ground from BlackBerry in latest US mobile comScore figures