It is used sometimes to describe a political move that leads to an unexpected win.

VOA: special.2009.02.15

She wanted to represent life on a ship in an unexpected way.

VOA: special.2010.06.11

But a person who threw a curve ball did something unexpected.

VOA: special.2009.04.12

Banks that received money from the Troubled Asset Relief Program reaped unexpected profits and repaid billions in loans, resulting in a record for the Federal Reserve.

VOA: standard.2010.01.15