What's The Nano Market?

$1 trillion by 2015? $3 trillion by 2017? Sky's the limit, it seems according to an article by Michael Berger about the widely varying figures for the global market for nano products. Concluding that such estimates can be "an irritating, sensationalist and unfortunate" approach to estimating economic worth, Berger asks that these predictions include a dose of reality along with some explanation of how the figures are generated.