According to the latest numbers from comScore, Android is the only major smartphoneOS that is growing, taking market from RIM, Apple, Microsoft and Palm.

comScore data

From February to May of this year, the Android platform grew an incredible 45%, from 9% of the total US smartphone market to 13%, according to comScore.  That share was pulled from the other four smartphone market leaders as shown by the chart at the right.

Overall, the smartphone market grew 8.1% according to comScore and all five platforms gained subscribers, though none obviously as significantly as Google GOOG .

Apple AAPL has released its annual iPhone product in June which should spur sales, which tend to taper off before major hardware releases.  Apple announced that it had sold 1.7 million units in the first three days of sales.  Apple also has two non-phone products that run its iOS software, the iPod and iPad which aren’t included in this report.

Google announced at the Droid x unveiling last month that it is activating 160,000 devices a day, up from 100,000/day in May.

While Android has been primarily focused on candy bar form factor devices, Samsung and Motorola are close to releasing Android products with Blackberry form factors. Those devices may help Google crack the massive Blackberry userbase.

Microsoft’s MSFT Windows Mobile platform has been dropping in market share as its partners await its Windows 7 Phone series, which is due in the Fall.

Palm was recently scooped up by HP HPQ who has promised to continue support the webOS platform, though no new products have been officially announced since the aquisition.

Although Android’s growth is phenomenal, it still has a long way to go to catch up with smartphone leaders Apple and RIM RIMM .  The graph below shows how far Android has yet to go before it challenges the two leaders.

US Smartphone marketshare. comScore data