• by Mark Walsh  @markfwal, November 3, 2010

ComScore is the latest research firm this week to chime in on the Great Smartphone Race, adding more evidence to underscore Android's continued proliferation. For the three months' average ending in September, the Google platform increased its share 6.5 percentage points to capture 21.4% of U.S. smartphone subscribers.

That gain came in part at the expense of BlackBerry-maker Research in Motion (RIM), which remains the leading smartphone operating system but saw its share slip from 40.1% to 37.3% in the third quarter.

Apple's iOS is still ahead of Google with almost a quarter of the market (24.3% share) but its growth was flat from the prior quarter. Microsoft, whose new Windows Phone 7 platform is just launching, dropped from a 12.8% to a 10% share of smartphone subscribers.

Earlier this week, NPD Group reported that Android was installed on 44% of U.S. smartphones sold in the third quarter, up 11 percentage points in the second quarter, compared to 23% for Apple and 22% for RIM. Separately, Nielsen reiterated that Android has been the best-selling smartphone OS over the last six months and pegged its market share at 19%, third behind Apple (28%) and RIM (30%) as of the third quarter.

So Nielsen's figures show a near dead heat for the top spot between RIM and Apple, while comScore shows the BlackBerry maker still holding a sizable, if shrinking, lead over Apple. The overall number of U.S. smartphone users grew 15% to 58.7 million people during the quarter, slightly improving on the 14% rate from the second quarter.

Looking at smartphone usage, the new comScore report showed no dramatic spikes -- but steady gains across different mobile data activities. The biggest jump was in the proportion of mobile users who used downloaded apps, which increased to 33.1% from 30.6% in the second quarter. Just over 35% browsed the mobile Web, 23.2% went to a social networking site or blog, 23.1% played games and 15.2% listened to music.

Among phone manufacturers, Samsung was again tops with a 23.5% share, followed by LG (21.2%), Motorola (18.4%), RIM (9.3%) and Nokia, (7.4%).

Clarification: The Nov. 2 Moblog post  should have said that 4.2 million iPads were sold during Apple's fiscal fourth quarter.