The two leaders in smartphone shipments, Apple Inc. (NASDAQ: AAPL) and Google Inc. (NASDAQ: GOOG), widened their lead over competitors in 2012, according to data released today by research firm Strategy Analytics. Android-based phones took 70% of the market and Apple captured 22%, leaving Research In Motion Ltd. (NASDAQ: RIMM), Nokia Corp. (NYSE: NOK) and Microsoft Corp. (NASDAQ: MSFT) fighting for scraps.

Just over 700 million smartphones were shipped in 2012, with 479 million Android phones going out the door, along with 135.8 million iPhones. Apple’s iOS share grew 29% year-over-year on a unit basis. Android OS-based phones actually doubled unit shipments year-over-year.

This data give some idea of the hurdles facing RIM and its new handset/operating system duo, the BlackBerry 10. First, the global market for smartphones is growing at a slower pace, up 43% in 2012 compared with a rise of 64% in 2011, according to Strategy Analytics. Second, the leaders — and their ecosystems — are so well established that dislodging or even grabbing share from one or the other won’t be easy or cheap.