Android designers have an expanding market share for their skill-sets. Comscore reported that more US smartphone users turned to Android in Q3 2011--some 44.8% of some 87 million users. Android's market share climbed 10%, rising from 40.2 % in Q2 to 44.8% in Q3 that ended Sept. 30 2011. Nielsen published similar numbers--placing it at 43% from 39% in Q2.
Certainly the fact that Android 1.) is open-source technology headed by Google and 2.) is running on many brands of smartphones from several vendors are two big reasons for the popularity of the mobile OS.
Research in Motion's share dropped to 18.9% from 23.5% for Q2.