Strategy Analytics estimates that 92% of global smartphone shipments in 2012 Q4 were iOS or Android.

• Android share : 51%(2011) -> 70%(2012)
• iOS share : 23.6%(2011) -> 22%(2012)

iOS’ market share has declined slightly, but the number of shipment units is grown.

• Android shipments : 80.6 million(2011) -> 152.1 million(2012)
• iOS shipments : 37 million(2011) -> 47.8 million(2012)

It seems like the duopoly of iOS + Android is getting stronger.

Android + iOS Grabbed 92% Of Global Smartphone Shipments In Q4 2012 — Android “Undisputed Volume Leader”, Says Analyst

The worldwide smartphone industry has effectively become a duopoly as consumer demand has polarized around mass-market Android models and premium Apple designs

However, many challengers including Microsoft, RIM, Firefox, Ubuntu are preparing for the new smartphone OS war, and it would be interesting to see how it goes.