It has been used a lot in business/management speak for almost 10 years I don't recall it being used before around 2004 so i'm not sure why it's use became so common.
orig. U.S. ‘Pay attention!’ ‘Watch out!’
1916 Daily Rev. (Decatur, Illinois) 8 Aug. 11/2 It is customary for the foreman of the crew to cry ‘Heads up’ as a warning, then the conductor signals the engineer to pull ahead about a car length.
Thank you all. Wherever it came from it shoul join phrases like, 'blue sky thinking' and 'run it up the flagpole and see who salutes', in some newspeak dustbin.