Worldwide shipments of mobile phones grew 21.7% in the first quarter, turbo-charged by the booming demand for smartphones, according to market research reports released Friday.

Research In Motion, which has always been strong in the smartphone category, rode the category to break into IDC's top-five market share finishers for the first time. RIM knocked Motorola from the top five list. IDC's Worldwide Mobile Phone Tracker reported that 294.9 million mobile phone handsets were shipped in the first quarter.

Also on Friday, market researcher Strategy Analytics reported that smartphone shipments jumped 50% during the quarter as Apple's iPhone shipments doubled, RIM held onto its 20% smartphone market share, and Nokia recorded its fastest growth rates in three years, helped by improved features like qwerty keyboards and touchscreens on Nokia mobile phones.

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— W. David Gardner, InformationWeek