Apple is grabbing mobile ad share from Google, Yahoo, Microsoft and Nokia

Smaller rivals like Jumptap and Millennial Media are also gaining, according to IDC

The pie chart at right is somewhat premature, given that it is IDC's best guess -- via
Bloomberg Businessweek
-- of what the $500 million U.S. mobile advertising market will look three months from now.

But it's an indication of how the winds have shifted. Apple (aapl), which had 0% share of the market before it bought Quattro Wireless in January and launched iAd in June, will end the year at 21%, according to IDC.

Where did that share come from? Chiefly from Google (goog), Yahoo (yhoo), Microsoft (msft) and Nokia (nok), according to the Businessweek piece.

IDC's before-and-after numbers for the biggest losers below the fold.

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Dec. 2009Dec. 2010

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[Follow Philip Elmer-DeWitt on Twitter @philiped]

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