comScore today released data from the comScore MobiLens service, reporting key trends in the U.S. mobile phone industry during the three month average period ending May 2010 compared to the preceding three-month average. The report ranked the leading mobile original equipment manufacturers (OEMs) and smartphone operating system (OS) platforms in the U.S. according to their share of current mobile subscribers age 13 and older, and reviewed the most popular activities and content accessed via the subscriber’s primary mobile phone. The May report found Samsung to be the top handset manufacturer overall with 22.4 percent market share, while RIM led among smartphone platforms with 41.7 percent market share.

MacDailyNews Take: It’s rather interesting that comScore would eschew the traditional quarters (Jan-Mar, Apr-Jun, etc.) and report instead on the odd March-May three month period. Now why would they do that? What happened in June that might make the data look different? Oh, right iPhone 4 launched in June. If you want a report that looks most advantageous to Apple’s “competitors,” you’d be hard pressed to concoct a better time period to measure than just before the launch of the new iPhone, especially since images and some specs had leaked out around the world in mid-April and likely killed a good portion of iPhone 3GS sales as informed buyers waited for iPhone 4. Now that you know the full story, here’s the rest of conScore, er… comScore’s report:

OEM Market Share

For the 3 month average period ending in May, 234 million Americans age 13 and older used mobile devices. Device manufacturer Samsung ranked as the top OEM with 22.4 percent of U.S. mobile subscribers, up one percentage point from the preceding three month period. LG ranked second with 21.5 percent share, followed by Motorola (21.2 percent share), RIM (8.7 percent share, up 0.5 percentage point) and Nokia (8.1 percent share).

Smartphone Platform Market Share

49.1 million people in the U.S. owned smartphones during the three months ending in May, up 8.1 percent from the corresponding February period. RIM was the leading mobile smartphone platform in the U.S. with 41.7 percent share of U.S. smartphone subscribers, followed by Apple with 24.4 percent share and Microsoft with 13.2 percent. Google rose 4.0 percentage points to capture 13.0 percent of smartphone subscribers, while Palm rounded out the top five with 4.8 percent. Most smartphone platforms continue to gain subscribers as the smartphone market overall continues to grow.

MacDailyNews Note: : The data abovedoes not include the impact of Apple’s launch of iPhone 4, which became available in June, but it does include the impact of lost iPhone sales due to the extensive leaks of iPhone 4 which started in mid-April.

Mobile Content Usage

65.2 percent of U.S. mobile subscribers used text messaging on their mobile device in May, up 1.4 percentage points versus the prior three month period, while browsers were used by 31.9 percent of U.S. mobile subscribers (up 2.3 percentage points). Subscribers who used downloaded applications comprised 30.0 percent of the mobile audience, representing an increase of 2.1 percentage points from the previous period. Accessing of social networking sites or blogs also saw significant growth, increasing 2.6 percentage points to 20.8 percent of mobile subscribers.

Source: comScore, Inc.